1.Exploration_with_CAS-I.Lab1_(1)[1].ppt
- 1. Exploration with CAS-I BMA151 Objectives: • To enhance the numerical computational skills of prospective engineers using open source software/ computer algebra system(CAS) SCILAB • To plot graphs of complicated functions .
- 2. Experiment-1:Starting with Scilab • Objectives: 1.1 What is SCILAB? 1.2. How to Install Scilab? 1.3.Working in the console 1.4.Arithmetic Operations with scalars 1.5.Elementary Math Build-in functions 1.6.Defining scalar variables 1.7.Script Files
- 3. Excercises • To write a Scilab code to find the solution of following problems: • 1. Evaluate: (i) 271/3+ 320.2 , (ii) , (iii) (iv) 4!+ln2+log100, (v) (2+3i)(4+5i) 2. By assigning values 2 and 5 to variables a and b respectively, compute (i) c=(a+b)2 (ii) d=4a-3b+lna+ c2 3.Write the script file for the problem: The radius of a circle is 2cm. Find its area. 4 64 e 0 sin cos60 6
- 4. 1.1 What is SCILAB • It is a software for Numerical computations 2D/3D Plotting. • It is free and open source software. • Available for various operating systems(OS) e.g. Windows, Linux and Mac OS/X • Its syntax is simple. • Many numerical problems can be expressed in a reduced number of code lines, as compared to similar solutions using traditional languages.
- 5. 1.1 What is SCILAB • It is a software for Numerical computations 2D/3D Plotting. • It is free and open source software. • Available for various operating systems(OS) e.g. Windows, Linux and Mac OS/X • Its syntax is simple. • Many numerical problems can be expressed in a reduced number of code lines, as compared to similar solutions using traditional languages.
- 6. Continued…. • CNES (French Space Satellite Agency) using Scilab successfully. • IIT Mumbai: Shifting all computational labs to Scilab
- 7. 1.2. How to Install Scilab • Visit: www.scilab.org. • Various versions of Scilab available for different Operating systems • Download the file as per the operating system in your computer. • And run it in your computer. • An icon of Scilab is created on your desktop. • Double click on the icon and we are in Scilab environment: File browser, console, variable browser and command history. • I am using scilab-6.0.1 for the windows platform in my system
- 8. 1.3.Working in the console • Console is the main window of Scilab • Used for executing commands(Instructions) • Opening other windows • Running programs written by the user • The ‘prompt’ : --> The horizontal inbuilt arrow on console is called prompt in front of which we write instruction(s) called command line. • role of ‘enter key’: We get the output of our calculations done on console by pressing the enter key. It is also used to write new command line • ‘ans=’ as the default variable:
- 9. Continued… • Role of commas , We can write Multiple commands on same command line separated by commas , --> 2,3,5 ans = 2. ans = 3. ans = 5. • Role of semicolon ; If a semicolon(;) is typed at the end of a command the output of the command is not displayed --> 2;3;5 ans = 5. • Role of commands: clc and clear clc is used to clear the console though data will still remain stored in the memory clear removes data from memory
- 10. 1.4.Arithmetic Operations with scalars Operation Scilab Symbol Example Addition + -->3+4 ans= 7 Subtraction - -->4-2 ans= 2 Multiplication * -->3*4 ans= 12 Division / -->3/4 ans= 0.75 Exponential ^ -->3^4 ans= 81 (means 34=81)
- 11. Order of precedence Precedence Mathematical Operation First Parenthesis (Brackets) Second Exponential Third Multiplication , Division( equal Precedence) Fourth Addition ,Subtraction( equal Precedence)
- 12. Exercises Compute: (i)7+8/2 (ii) (7+8)/2 (iii) ( 4+2X5)/7 (iv) 271/3+ 320.2 (Answrs: (i)11, (ii)7.5, (iii)2, (iv) 5
- 13. 1.5.Elementary Math Build-in functions Function Description Scilab Command Example Square root sqrt(x) -->sqrt(81) ans= 9 Real nth root of a real number x nthroot(x,n) -->nthroot(80,5) ans= 2.4022489 Exponential(ex) exp(x) -->exp(5) ans= 148.41316 Natural log(base e). ln log(x) -->log(1000) ans= 6.9078 Base 10 logarithm. log log10(x) -->log10(1000) ans= 3.0000
- 14. Continued… Function Description Scilab Command Example x! factorial(x) -->factorial(5) ans= 120 %pi -->%pi/3 ans= 1.0471976 Complex number %i -->2+3*%i ans= 2. + 3.i Sine of angle x (x in radians) sin(x) -->sin(%pi/6) ans= 0.5 Sine of angle x (x in degrees) sind(x) -->sind(30) ans= 0.5 1 i
- 15. 1.6.Defining scalar variables • A variable is a name made of a letter or a combination of several letters that is assigned a numerical value. • = sign is called the assignment operator. It assigns a value to a variable. • x=15 means the number 15 is assigned to the variable x • A variable is actually a name of memory location where the variable’s assignment is stored .
- 16. 1.7.Script Files • Why we need Script files? • Using the console to execute a series of commands is not convenient: (i)The commands in the console can not be saved and executed again. (ii) Every time the enter key is pressed only the last command is executed, and everything executed before is unchanged. We can not edit the previous commands.
- 17. 1.7.Script Files(Continued…) • What are Script files? • A different(better) way of executing commands is first to create a file with a list of commands(program), save it, and then run(execute) the file. • A script file is a sequence of Scilab commands( also called a program) • When a script file runs, Scilab executes the commands in the order they are written just as if they were typed in the console. • When a script file has a command that generates an out put, the output is displayed in the console. • Using an script file is convenient because it can be edited and executed many times. • Script files can be typed and edited in any text editor and then pasted in to the scilab editor(also called scinotes)
- 18. 1.7.Script Files(Continued…) • Creating, saving and executing a Script file • Scilab script files are created and edited in the editor window( also called scinotes window) • To Open the Editor: Click on the Launch SciNotes icon of the toolbar given at the top • Creating script file: Compute: a=(4+2X5)/7 • To save our work done on editor: Click on the save as icon of the toolbar given at the top. select the folder(or Create a new folder) > name the file > select save.
- 19. 1.7.Script Files(Continued…) • Creating, saving and executing a Script file (continued…) • Command line for display of the output of our computation a done on Editor on console: disp(a) or disp(a, ‘a=‘) • Click on the save and execute icon on the tool bar of the Editor. • Go to the console and you will see the output displayed there. • To Open our SciNotes files: Click on the open icon given on the tool bar of the Editor > select the file to be opened > select open