Algoritmicx

The algorithmicx package∗
Sz´sz Jńos
a a
szaszjanos@users.sourceforge.net
November 28, 2012

Abstract
The algorithmicx package provides many possibilities to customize
the layout of algorithms. You can use one of the predefined layouts
(pseudocode, pascal and c and others), with or without modifications,
or you can define a completely new layout for your specific needs.

Contents
1 Introduction 1

2 General informations 2
2.1 The package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2 The algorithmic block . . . . . . . . . . . . . . . . . . . . . . . . 2
2.3 Simple lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.4 Placing comments in sources . . . . . . . . . . . . . . . . . . . . 3
2.5 Labels and references . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.6 Breaking up long algorithms . . . . . . . . . . . . . . . . . . . . . 3
2.7 Multiple layouts in the same document . . . . . . . . . . . . . . . 4

3 The predefined layouts 4
3.1 The algpseudocode layout . . . . . . . . . . . . . . . . . . . . . 4
3.1.1 The for block . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.2 The while block . . . . . . . . . . . . . . . . . . . . . . . 6
3.1.3 The repeat block . . . . . . . . . . . . . . . . . . . . . . 6
3.1.4 The if block . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.5 The procedure block . . . . . . . . . . . . . . . . . . . . 7
3.1.6 The function block . . . . . . . . . . . . . . . . . . . . . 7
3.1.7 The loop block . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.8 Other commands in this layout . . . . . . . . . . . . . . . 8
3.1.9 Package options . . . . . . . . . . . . . . . . . . . . . . . . 8
∗ This is the documentation for the version 1.2 of the package. This package is released

under LPPL.

1

3.1.10 Changing command names . . . . . . . . . . . . . . . . . 9
3.2 The algpascal layout . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.1 The begin . . . end block . . . . . . . . . . . . . . . . . . 10
3.2.2 The for loop . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.3 The while loop . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.4 The repeat. . . until block . . . . . . . . . . . . . . . . . 11
3.2.5 The if command . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.6 The procedure command . . . . . . . . . . . . . . . . . . 11
3.2.7 The function command . . . . . . . . . . . . . . . . . . . 11
3.3 The algc layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

4 Custom algorithmic blocks 12
4.1 Blocks and loops . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Defining blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Defining loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.4 Continuing blocks and loops . . . . . . . . . . . . . . . . . . . . . 15
4.5 Even more customisation . . . . . . . . . . . . . . . . . . . . . . 16
4.6 Parameters, custom text . . . . . . . . . . . . . . . . . . . . . . . 18
4.7 The ONE defining macro . . . . . . . . . . . . . . . . . . . . . . 19

5 Examples 21
5.1 A full example using algpseudocode . . . . . . . . . . . . . . . 21
5.2 Breaking up an algorithm . . . . . . . . . . . . . . . . . . . . . . 23
5.3 Using multiple layouts . . . . . . . . . . . . . . . . . . . . . . . . 25

6 Bugs 27

1 Introduction
All this has begun in my last year at the university. The only thing that I knew
of L TEX was that it exists, and that it is “good”. I started using it, but I needed
A

to typeset some algorithms. So I begun searching for a good algorithmic style,
and I have found the algorithmic package. It was a great joy for me, and I
started to use it. . . Well. . . Everything went nice, until I needed some block
that wasn’t defined in there. What to do? I was no L TEX guru, in fact I only
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knew the few basic macros. But there was no other way, so I opened the style
file, and I copied one existing block, renamed a few things, and voil`! This (and
a
some other small changes) where enough for me. . .
One year later — for one good soul — I had to make some really big changes
on the style. And there on a sunny day came the idea. What if I would write
some macros to let others create blocks automatically? And so I did! Since then
the style was completely rewritten. . . several times. . .
I had fun writing it, may you have fun using it! I am still no L TEX guru, so
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if you are, and you find something really ugly in the style, please mail me! All
ideas for improvements are welcome!

2

Thanks go to Benedek Zsuzsa, Ionescu Clara, Sz˝cs Zoltń, Cseke Botond,
o a
Kanoc and many-many others. Without them I would have never started or
continued algorithmicx.

2 General informations
2.1 The package
The package algorithmicx itself doesn’t define any algorithmic commands,
but gives a set of macros to define such a command set. You may use only
algorithmicx, and define the commands yourself, or you may use one of the
predefined command sets.
These predefined command sets (layouts) are:
algpseudocode has the same look1 as the one defined in the algorithmic
package. The main difference is that while the algorithmic package
doesn’t allow you to modify predefined structures, or to create new ones,
the algorithmicx package gives you full control over the definitions (ok,
there are some limitations — you can not send mail with a, say, For
command).
algcompatible is fully compatible with the algorithmic package, it should
be used only in old documents.
algpascal aims to create a formatted pascal program, it performs automatic
indentation (!), so you can transform a pascal program into an algpascal
algorithm description with some basic substitution rules.
algc – yeah, just like the algpascal. . . but for c. . . This layout is incomplete.
To create floating algorithms you will need algorithm.sty. This file may or
may not be included in the algorithmicx package. You can find it on CTAN,
in the algorithmic package.

2.2 The algorithmic block
Each algorithm begins with the begin{algorithmic}[lines] command, the
optional lines controls the line numbering: 0 means no line numbering, 1
means number every line, and n means number lines n, 2n, 3n. . . until the
end{algorithmic} command, witch ends the algorithm.

2.3 Simple lines
A simple line of text is beginned with State. This macro marks the begin
of every line. You don’t need to use State before a command defined in the
package, since these commands use automatically a new line.
1 almost :-)

3

To obtain a line that is not numbered, and not counted when counting the
lines for line numbering (in case you choose to number lines), use the Statex
macro. This macro jumps into a new line, the line gets no number, and any
label will point to the previous numbered line.
We will call stataments the lines starting with State. The Statex lines
are not stataments.

2.4 Placing comments in sources
Comments may be placed everywhere in the source using the Comment macro
(there are no limitations like those in the algorithmic package), feel the free-
dom! If you would like to change the form in witch comments are displayed,
just change the algorithmiccomment macro:

algrenewcommand{algorithmiccomment}[1]{hskip3em$rightarrow$ #1}

will result:
1: x←x+1 → Here is the new comment

2.5 Labels and references
Use the label macro, as usual to label a line. When you use ref to reference
the line, the ref will be subtitued with the corresponding line number. When
using the algorithmicx package togedher with the algorithm package, then
you can label both the algorithm and the line, and use the algref macro to
reference a given line from a given algorithm:

algref{<algorithm>}{<line>}

The textbf{while} in algorithm The while in algorithm 1 ends in line 7,
ref{euclid} ends in line so 1.7 is the line we seek.
ref{euclidendwhile}, so
algref{euclid}{euclidendwhile}
is the line we seek.

2.6 Breaking up long algorithms
Sometimes you have a long algorithm that needs to be broken into parts, each
on a separate ﬂoat. For this you can use the following:

algstore{<savename>} saves the line number, indentation, open blocks of
the current algorithm and closes all blocks. If used, then this must be the
last command before closing the algorithmic block. Each saved algorithm
must be continued later in the document.
algstore*{<savename>} Like the above, but the algorithm must not be con-
tinued.

4

algrestore{<savename>} restores the state of the algorithm saved under
<savename> in this algorithmic block. If used, then this must be the first
command in an algorithmic block. A save is deleted while restoring.
algrestore*{<savename>} Like the above, but the save will not be deleted,
so it can be restored again.

See example in the Examples section.

2.7 Multiple layouts in the same document
You can load multiple algorithmicx layouts in the same document. You can
switch between the layouts using the alglanguage{<layoutname>} command.
After this command all new algorithmic environments will use the given layout
until the layout is changed again.

3 The predefined layouts
3.1 The algpseudocode layout
If you are familiar with the algorithmic package, then you’ll find it easy to
switch. You can use the old algorithms with the algcompatible layout, but
please use the algpseudocode layout for new algorithms.
To use algpseudocode, simply load algpseudocode.sty:

usepackage{algpseudocode}

You don’t need to manually load the algorithmicx package, as this is done
by algpseudocode.
The first algorithm one should write is the first algorithm ever (ok, an im-
proved version), Euclid’s algorithm:

Algorithm 1 Euclid’s algorithm
1: procedure Euclid(a, b) The g.c.d. of a and b
2: r ← a mod b
3: while r = 0 do We have the answer if r is 0
4: a←b
5: b←r
6: r ← a mod b
7: end while
8: return b The gcd is b
9: end procedure

Created with the following source:

5

begin{algorithm}
caption{Euclid’s algorithm}label{euclid}
begin{algorithmic}[1]
Procedure{Euclid}{$a,b$}Comment{The g.c.d. of a and b}
State $rgets abmod b$
While{$rnot=0$}Comment{We have the answer if r is 0}
State $agets b$
State $bgets r$
State $rgets abmod b$
EndWhilelabel{euclidendwhile}
State textbf{return} $b$Comment{The gcd is b}
EndProcedure
end{algorithmic}
end{algorithm}
The State stands at the beginning of each simple statement; the respective
statement is put in a new line, with the needed indentation. The Procedure
. . . EndProcedure and While . . . EndWhile blocks (like any block defined in
the algpseudocode layout) automatically indent their content. The indenta-
tion of the source doesn’t matter, so
Repeat 1: repeat forever
Comment{forever} 2: this
State thisUntil{you die.} 3: until you die.
end{algorithmic}

But, generally, it is a good idea to keep the source indented, since you will
find errors much easier. And your tex file looks better!
All examples and syntax descriptions will be shown as the previous example
— the left side shows the L TEX input, and the right side the algorithm, as it
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appears in your document. I’m cheating! Don’t look in the algorithmicx.tex
file! Believe what the examples state! I may use some undocumented and dirty
stuff to create all these examples. You might be more confused after opening
algorithmicx.tex as you was before.
In the case of syntax descriptions the text between < and > is symbolic,
so if you type what you see on the left side, you will not get the algorithm on
the right side. But if you replace the text between < > with a proper piece of
algorithm, then you will probably get what you want. The parts between [ and
] are optional.

3.1.1 The for block
The for block may have one of the forms:
For{<text>} 1: for <text> do
<body> 2: <body>
EndFor 3: end for

6

ForAll{<text>} 1: for all <text> do
<body> 2: <body>
EndFor 3: end for

Example:
State $sumgets 0$ 1: sum ← 0
For{$igets 1, n$} 2: for i ← 1, n do
State $sumgets sum+i$ 3: sum ← sum + i
EndFor 4: end for
end{algorithmic}

3.1.2 The while block
The while block has the form:
While{<text>} 1: while <text> do
<body> 2: <body>
EndWhile 3: end while

Example:
State $igets 1$ 2: i←1
While{$ile n$} 3: while i ≤ n do
State $igets i+1$ 5: i←i+1
end{algorithmic}

3.1.3 The repeat block
The repeat block has the form:
Repeat 1: repeat
<body> 2: <body>
Until{<text>} 3: until <text>

Example:
State $igets 1$ 2: i←1
Repeat 3: repeat
State $igets i+1$ 5: i←i+1
Until{$i>n$} 6: until i > n
end{algorithmic}

7

3.1.4 The if block
The if block has the form:
If{<text>} 1: if <text> then
<body> 2: <body>
[ [
ElsIf{<text>} 3: else if <text> then
<body> 4: <body>
... ...
] ]
[ [
Else 5: else
<body> 6: <body>
] ]
EndIf 7: end if

Example:

If{$qualityge 9$} 1: if quality ≥ 9 then
State $agets perfect$ 2: a ← perf ect
ElsIf{$qualityge 7$} 3: else if quality ≥ 7 then
State $agets good$ 4: a ← good
State $agets medium$ 6: a ← medium
State $agets bad$ 8: a ← bad
Else 9: else
State $agets unusable$ 10: a ← unusable
EndIf 11: end if
end{algorithmic}

3.1.5 The procedure block
The procedure block has the form:

Procedure{<name>}{<params>} 1: procedure <name>(<params>)
<body> 2: <body>
EndProcedure 3: end procedure

Example: See Euclid’s algorithm on page 4.

3.1.6 The function block
The function block has the same syntax as the procedure block:

8

Function{<name>}{<params>} 1: function <name>(<params>)
<body> 2: <body>
EndFunction 3: end function

3.1.7 The loop block
The loop block has the form:

Loop 1: loop
<body> 2: <body>
EndLoop 3: end loop

3.1.8 Other commands in this layout
The starting conditions for the algorithm can be described with the require
instruction, and its result with the ensure instruction.
A procedure call can be formatted with Call.

Require something Require: something
Ensure something Ensure: something
Statex
State Call{Create}{10} 1: Create(10)

Example:

Require $xge5$ Require: x ≥ 5
Ensure $xle-5$ Ensure: x ≤ −5
Statex
While{$x>-5$} 1: while x > −5 do
State $xgets x-1$ 2: x←x−1
end{algorithmic}

3.1.9 Package options
The algpseudocode package supports the following options:

compatible/noncompatible Obsolote, use the algcompatible layout instead.
If you would like to use old algorithms, written with the algorithmic
package without (too much) modification, then use the compatible op-
tion. This option defines the uppercase version of the commands. Note
that you still need to remove the [...] comments (these comments ap-
peared due to some limitations in the algorithmic package, these limi-
tations and comments are gone now). The default noncompatible does
not define the all uppercase commands.

9

noend/end
With noend speciﬁed all end . . . lines are omitted. You get a somewhat
smaller algorithm, and the ugly feeling, that something is missing. . . The
end value is the default, it means, that all end . . . lines are in their right
place.

3.1.10 Changing command names
One common thing for a pseudocode is to change the command names. Many
people use many diﬀerent kind of pseudocode command names. In algpseu-
docode all keywords are declared as algorithmic<keyword>. You can change
them to output the text you need:

algrenewcommandalgorithmicwhile{textbf{am’i g}}
algrenewcommandalgorithmicdo{textbf{v’egezd el}}
algrenewcommandalgorithmicend{textbf{v’ege}}
State $x gets 1$ 1: x ← 1
While{$x < 10$} 2: am´ x < 10 v´gezd el
ıg e
State $x gets x + 1$ 3: x←x+1
EndWhile 4: v´ge am´
e ıg
end{algorithmic}

In some cases you may need to change even more (in the above example
am´ and v´ge should be interchanged in the EndWhile text). Maybe the
ıg e
number of the parameters taken by some commands must be changed too. this
can be done with the command text customizing macros (see section 4.6). Here
I’ll give only some examples of the most common usage:

algrenewcommandalgorithmicwhile{textbf{am’i g}}
algrenewcommandalgorithmicdo{textbf{v’egezd el}}
algrenewcommandalgorithmicend{textbf{v’ege}}
algrenewtext{EndWhile}{algorithmicwhile algorithmicend}
State $x gets 1$ 1: x ← 1
While{$x < 10$} 2: am´ x < 10 v´gezd el
ıg e
State $x gets x - 1$ 3: x←x−1
EndWhile 4: am´ v´ge
ıg e
end{algorithmic}

10

algnewcommandalgorithmicto{textbf{to}}
algrenewtext{For}[3]%
{algorithmicfor #1 gets #2 algorithmicto #3 algorithmicdo}
State $p gets 1$ 1: p ← 1
For{i}{1}{n} 2: for i ← 1 to n do
State $p gets p * i$ 3: p←p∗i
EndFor 4: end for
end{algorithmic}

You could create a translation package, that included after the algpseu-
docode package translates the keywords to the language you need.

3.2 The algpascal layout
The most important feature of the algpascal layout is that it performs auto-
matically the block indentation. In section 4 you will see how to deﬁne such
automatically indented loops. Here is an example to demonstrate this feature:

Begin 1: begin
State $sum:=0$; 2: sum := 0;
For{i=1}{n}Comment{sum(i)} 3: for i = 1 to n do {sum(i)}
State $sum:=sum+i$; 4: sum := sum + i;
State writeln($sum$); 5: writeln(sum);
End. 6: end.
end{algorithmic}

Note, that the For is not closed explicitly, its end is detected automatically.
Again, the indentation in the source doesn’t aﬀect the output. In this layout
every parameter passed to a command is put in mathematical mode.

3.2.1 The begin . . . end block
Begin 1: begin
<body> 2: <body>
End 3: end

The Begin . . . End block and the Repeat . . . Until block are the
only blocks in the algpascal style (instead of Begin you may write Asm).
This means, that every other loop is ended automatically after the following
command (another loop, or a block).

3.2.2 The for loop
For{<assign>}{<expr>} 1: for <assign> to <expr> do
<command> 2: <command>

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The For loop (as all other loops) ends after the following command (a block
counts also as a single command).

Begin 1: begin
State $sum:=0$; 2: sum := 0;
State $prod:=1$; 3: prod := 1;
For{i:=1}{10} 4: for i := 1 to 10 do
Begin 5: begin
State $sum:=sum+i$; 6: sum := sum + i;
State $prod:=prod*i$; 7: prod := prod ∗ i;
End 8: end
End. 9: end.
end{algorithmic}

3.2.3 The while loop
While{<expression>} 1: while <expression> do

3.2.4 The repeat. . . until block
Repeat 1: repeat
<body> 2: <body>
Until{<expression>} 3: until <expression>

3.2.5 The if command
If{<expression>} 1: if <expression> then
[ [
Else 3: else
] ]

Every Else matches the nearest If.

3.2.6 The procedure command
Procedure <some text> 1: procedure <some text>

Procedure just writes the “procedure” word on a new line... You will
probably put a Begin. . . End block after it.

3.2.7 The function command
Function<some text> 1: function <some text>

Just like Procedure.

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3.3 The algc layout
Sorry, the algc layout is unfinished. The commands defined are:

• {. . . } block
• For with 3 params

• If with 1 param
• Else with no params
• While with 1 param
• Do with no params

• Function with 3 params
• Return with no params

4 Custom algorithmic blocks
4.1 Blocks and loops
Most of the environments defined in the standard layouts (and most probably
the ones you will define) are divided in two categories:

Blocks are the environments witch contain an arbitrary number of commands
or nested blocks. Each block has a name, begins with a starting command
and ends with an ending command. The commands in a block are indented
by algorithmicindent (or another amount).
If your algorithm ends without closing all blocks, the algorithmicx pack-
age gives you a nice error. So be good, and close them all!
Blocks are all the environments defined in the algpseudocode package,
the Begin . . . End block in the algpascal package, and some other ones.
Loops (Let us call them loops. . . ) The loops are environments that include
only one command, loop or block; a loop is closed automatically after this
command. So loops have no ending commands. If your algorithm (or a
block) ends before the single command of a loop, then this is considered
an empty command, and the loop is closed. Feel free to leave open loops
at the end of blocks!
Loops are most of the environments in the algpascal and algc packages.

For some rare constructions you can create mixtures of the two environments
(see section 4.5). Each block and loop may be continued with another one (like
the If with Else).

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4.2 Defining blocks
There are several commands to define blocks. The difference is in what is defined
beyond the block. The macro algblock defines a new block with starting and
ending entity.

algblock[<block>]{<start>}{<end>}

The defined commands have no parameters, and the text displayed by them
is textbf{<start>} and textbf{<end>}. You can change these texts later
(4.6).
With algblockdefx you can give the text to be output by the starting and
ending command and the number of parameters for these commands. In the
text reference with #n to the parameter number n. Observe that the text is
given in the form you define or redefine macros, and really, this is what happens.

algblockdefx[<block>]{<start>}{<end>}
[<startparamcount>][<default value>]{<start text>}
[<endparamcount>][<default value>]{<end text>}

This defines a new block called <block>, <start> opens the block, <end>
closes the block, <start> displays <start text>, and has <startparamcount>
parameters, <end> displays <end text>, and has <endparamcount> parame-
ters. For both <start> and <end>, if <default value> is given, then the first
parameter is optional, and its default value is <default value>.
If you want to display different text (and to have a different number of param-
eters) for <end> at the end of different blocks, then use the algblockx macro.
Note that it is not possible to display different starting texts, since it is not possi-
ble to start different blocks with the same command. The <start text> defined
with algblockx has the same behavior as if defined with algblockdefx. All
ending commands not defined with algblockx will display the same text, and
the ones defined with this macro will display the different texts you specified.

algblockx[<block>]{<start>}{<end>}

If in the above definitions the <block> is missing, then the name of the
starting command is used as block name. If a block with the given name already
exists, these macros don’t define a new block, instead this it will be used the
defined block. If <start> or <end> is empty, then the definition does not define
a new starting/ending command for the block, and then the respective text
must be missing from the definition. You may have more starting and ending
commands for one block. If the block name is missing, then a starting command
must be given.

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algblock[Name]{Start}{End}
algblockdefx[NAME]{START}{END}%
[2][Unknown]{Start #1(#2)}%
{Ending}
algblockdefx[NAME]{}{OTHEREND}%
[1]{Until (#1)}
Start 1: Start
Start 2: Start
START[One]{x} 3: Start One(x)
END 4: Ending
START{0} 5: Start Unknown(0)
OTHEREND{texttt{True}} 6: Until (True)
End 7: End
Start 8: Start
End 9: End
End 10: End
end{algorithmic}

4.3 Defining loops
The loop defining macros are similar to the block defining macros. A loop has
no ending command and ends after the first state, block or loop that follows the
loop. Since loops have no ending command, the macro algloopx would not
have mutch sense. The loop defining macros are:

algloop[<loop>]{<start>}

algloopdefx[<loop>]{<start>}

Both create a loop named <loop> with the starting command <start>. The
second also sets the number of parameters, and the text displayed by the starting
command.

15

algloop{For}
algloopdefx{If}[1]{textbf{If} #1 textbf{then}}
algblock{Begin}{End}
For 1: For
Begin 2: Begin
If{$a < b$} 3: If a < b then
For 4: For
Begin 5: Begin
End 6: End
Begin 7: Begin
End 8: End
End 9: End
end{algorithmic}

4.4 Continuing blocks and loops
For each block/loop you may give commands that close the block or loop and
open another block or loop. A good example for this is the if . . . then . . . else
construct. The new block or loop can be closed or continued, as any other blocks
and loops.
To create a continuing block use one of the following:

algcblock[<new block>]{<old block>}{<continue>}{<end>}

algcblockdefx[<new block>]{<old block>}{<continue>}{<end>}
[<continueparamcount>][<default value>]{<continue text>}

algcblockx[<new block>]{<old block>}{<continue>}{<end>}

All three macros define a new block named <new block>. If <new block>
is not given, then <continue> is used as the new block name. It is not allowed
to have both <new block> missing, and <continue> empty. The <continue>
command ends the <old block> block/loop and opens the <new block> block.
Since <continue> may end different blocks and loops, it can have different text
at the end of the different blocks/loops. If the <continue> command doesn’t
find an <old block> to close, then an error is reported.
Create continuing loops with the followings:

algcloop[<new loop>]{<old block>}{<continue>}

algcloopdefx[<new loop>]{<old block>}{<continue>}

16

algcloopx[<new loop>]{<old block>}{<continue>}

These macros create a continuing loop, the <continue> closes the <old block>
block/loop, and opens a <new loop> loop.

algblock{If}{EndIf}
algcblock[If]{If}{ElsIf}{EndIf}
algcblock{If}{Else}{EndIf}
algcblockdefx[Strange]{If}{Eeee}{Oooo}
[1]{textbf{Eeee} "#1"}
{textbf{Wuuuupsdots}}
If 1: If
If 2: If
ElsIf 3: ElsIf
ElsIf 4: ElsIf
If 5: If
ElsIf 6: ElsIf
Else 7: Else
EndIf 8: EndIf
EndIf 9: EndIf
If 10: If
EndIf 11: EndIf
Eeee{Creep} 12: Eeee ”Creep”
Oooo 13: Wuuuups. . .
end{algorithmic}

algloop{If}
algcloop{If}{Else}
algblock{Begin}{End}
If 1: If
Begin 2: Begin
End 3: End
Else 4: Else
If 5: If
Begin 6: Begin
End 7: End
end{algorithmic}

4.5 Even more customisation
With the following macros you can give the indentation used by the new block
(or loop), and the number of stataments after that the ”block” is automatically

17

closed. This value is ∞ for blocks, 1 for loops, and 0 for stataments. There is a
special value, 65535, meaning that the defined ”block” does not end automat-
ically, but if it is enclosed in a block, then the ending command of the block
closes this ”block” as well.

algsetblock[<block>]{<start>}{<end>}
{<lifetime>}{<indent>}

algsetblockdefx[<block>]{<start>}{<end>}

algsetblockx[<block>]{<start>}{<end>}

algcsetblock[<new block>]{<old block>}{<continue>}{<end>}

algcsetblockdefx[<new block>]{<old block>}{<continue>}{<stop>}

algcsetblockx[<new block>]{<old block>}{<continue>}{<stop>}

The <lifetime> is the number of stataments after that the block is closed.
An empty <lifetime> field means ∞. The <indent> gives the indentation of
the block. Leave this field empty for the default indentation. The rest of the
parameters has the same function as for the previous macros.

18

algsetblock[Name]{Start}{Stop}{3}{1cm}
algsetcblock[CName]{Name}{CStart}{CStop}{2}{2cm}
Start 1: Start
State 1 2: 1
State 2 3: 2
State 3 4: 3
State 4 5: 4
Start 6: Start
State 1 7: 1
Stop 8: Stop
State 2 9: 2
Start 10: Start
State 1 11: 1
CStart 12: CStart
State 1 13: 1
State 2 14: 2
State 3 15: 3
Start 16: Start
State 1 17: 1
CStart 18: CStart
State 1 19: 1
CStop 20: CStop
end{algorithmic}

The created environments behave as follows:

• It starts with Start. The nested environments are indented by 1 cm.
• If it is followed by at least 3 environments (stataments), then it closes
automatically after the third one.
• If you put a Stop before the automatic closure, then this Stop closes
the environment. CStart closes a block called Name and opens a new one
called CName and having an indentaion of 2 cm.
• CName can be closed with CStop or it is closed automatically after 2 envi-
ronments.

4.6 Parameters, custom text
With algrenewtext you can change the number of parameters, and the text
displayed by the commands. With algnotext you can makes the vole output
line disappear, but it works only for ending commands, for beginning commands
you will get an incorrect output.

algrenewcommand[<block>]{<command>}
[<paramcount>][<default value>]{<text>}

19

algnotext[<block>]{<ending command>}

If <block> is missing, then the default text is changed, and if <block> is
given, then the text displayed at the end of <block> is changed.
To make a command output the default text at the end of a block (say, you
have changed the text for this block), use algdefaulttext.

algdefaulttext[<block>]{<command>}

If the <block> is missing, than the default text itself will be set to the default
value (this is textbf{<command>}).

4.7 The ONE defining macro
All block and loop defining macros call the same macro. You may use this macro
to gain a better acces to what will be defined. This macro is algdef.

algdef{<flags>}...

Depending on the flags the macro can have many forms.

Flag Meaning
s starting command, without text
S starting command with text
c continuing command, without text
C continuing command, with default text
xC continuing command, with block specific text
e ending command, without text
E continuing command, with default text
xE continuing command, with block specific text
N ending command, with default ”no text”
xN ending command, with no text for this block
b block(default)
l loop
L loop closes after the given number of stataments
i indentation specified

The <new block> may be given for any combination of flags, and it is not
allowed to have <new block> missing and <start> missing/empty. For c, C,
xC an old block is expected. For s, S, c, C, xC the <start> must be given.
For e, E, xE, N, xN the <end> must be given. For L the <lifetime> must be
given. For i the <indent> must be given. For S, C, xC the starting text and
related infos must be given. For E, xE the ending text must be given. For each
combination of flags give only the needed parameters, in the following order:

20

algdef{<flags>}[<new block>]{<old block>}{<start>}{<end>}

The block and loop deﬁning macros call algdef with the following ﬂags:

Macro Meaning
algblock algdef{se}
algcblock algdef{ce}
algloop algdef{sl}
algcloop algdef{cl}
algsetblock algdef{seLi}
algsetcblock algdef{ceLi}
algblockx algdef{SxE}
algblockdefx algdef{SE}
algcblockx algdef{CxE}
algcblockdefx algdef{CE}
algsetblockx algdef{SxELi}
algsetblockdefx algdef{SELi}
algsetcblockx algdef{CxELi}
algsetcblockdefx algdef{CELi}
algloopdefx algdef{Sl}
algcloopx algdef{Cxl}
algcloopdefx algdef{Cl}

21

5 Examples
5.1 A full example using algpseudocode
documentclass{article}
usepackage{algorithm}
begin{document}
begin{algorithm}
caption{The Bellman-Kalaba algorithm}
Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
ForAll {$v in V(G)$}
State $l(v) leftarrow infty$
EndFor
State $l(u) leftarrow 0$
Repeat
For {$i leftarrow 1, n$}
State $min leftarrow l(v_i)$
For {$j leftarrow 1, n$}
If {$min > e(v_i, v_j) + l(v_j)$}
State $min leftarrow e(v_i, v_j) + l(v_j)$
State $p(i) leftarrow v_j$
EndIf
EndFor
State $l’(i) leftarrow min$
EndFor
State $changed leftarrow l not= l’$
State $l leftarrow l’$
Until{$neg changed$}
EndProcedure
Statex
Procedure {FindPathBK}{$v$, $u$, $p$}
If {$v = u$}
State textbf{Write} $v$
Else
State $w leftarrow v$
While {$w not= u$}
State textbf{Write} $w$
State $w leftarrow p(w)$
EndWhile
EndIf
EndProcedure
end{algorithmic}
end{algorithm}
end{document}

22

Algorithm 2 The Bellman-Kalaba algorithm
1: procedure BellmanKalaba(G, u, l, p)
2: for all v ∈ V (G) do
3: l(v) ← ∞
4: end for
5: l(u) ← 0
6: repeat
7: for i ← 1, n do
8: min ← l(vi )
9: for j ← 1, n do
10: if min > e(vi , vj ) + l(vj ) then
11: min ← e(vi , vj ) + l(vj )
12: p(i) ← vj
13: end if
14: end for
15: l (i) ← min
16: end for
17: changed ← l = l
18: l←l
19: until ¬changed
20: end procedure

21: procedure FindPathBK(v, u, p)
22: if v = u then
23: Write v
24: else
25: w←v
26: while w = u do
27: Write w
28: w ← p(w)
29: end while
30: end if
31: end procedure

23

5.2 Breaking up an algorithm
begin{document}
begin{algorithm}
caption{Part 1}
Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
ForAll {$v in V(G)$}
State $l(v) leftarrow infty$
EndFor
State $l(u) leftarrow 0$
Repeat
For {$i leftarrow 1, n$}
State $min leftarrow l(v_i)$
For {$j leftarrow 1, n$}
If {$min > e(v_i, v_j) + l(v_j)$}
State $min leftarrow e(v_i, v_j) + l(v_j)$
State Comment For some reason we need to break here!
algstore{bkbreak}
end{algorithmic}
end{algorithm}

And we need to put some additional text betweendots

begin{algorithm}[h]
caption{Part 2}
algrestore{bkbreak}
State $p(i) leftarrow v_j$
EndIf
EndFor
State $l’(i) leftarrow min$
EndFor
State $changed leftarrow l not= l’$
State $l leftarrow l’$
Until{$neg changed$}
EndProcedure
end{algorithmic}
end{algorithm}
end{document}

24

Algorithm 3 Part 1
1: procedure BellmanKalaba(G, u, l, p)
2: for all v ∈ V (G) do
3: l(v) ← ∞
4: end for
5: l(u) ← 0
6: repeat
7: for i ← 1, n do
8: min ← l(vi )
9: for j ← 1, n do
10: if min > e(vi , vj ) + l(vj ) then
11: min ← e(vi , vj ) + l(vj )
12: For some reason we need to break here!

And we need to put some additional text between. . .

Algorithm 4 Part 2
13: p(i) ← vj
14: end if
15: end for
16: l (i) ← min
17: end for
18: changed ← l = l
19: l←l
20: until ¬changed
21: end procedure

25

5.3 Using multiple layouts
usepackage{algpascal}
begin{document}

alglanguage{pseudocode}
begin{algorithm}
caption{A small pseudocode}
State $s gets 0$
State $p gets 0$
For{$i gets 1,, 10$}
State $s gets s + i$
State $p gets p + s$
EndFor
end{algorithmic}
end{algorithm}

alglanguage{pascal}
begin{algorithm}
caption{The pascal version}
State $s := 0$
State $p := 0$
For{i = 1}{10}
Begin
State $s := s + i$
State $p := p + s$
End
end{algorithmic}
end{algorithm}

end{document}

26

Algorithm 5 A small pseudocode
1: s ← 0
2: p ← 0
3: for i ← 1, 10 do
4: s←s+i
5: p←p+s
6: end for

Algorithm 6 The pascal version
1: s := 0
2: p := 0
3: for i = 1 to 10 do
4: begin
5: s := s + i
6: p := p + s
7: end

27

6 Bugs
If you have a question or ﬁnd a bug you can contact me on:
szaszjanos@users.sourceforge.net
If possible, please create a small L TEX example related to your problem.
A

28

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