Cape2013 scilab-workshop-19Oct13

P. R. Naren
School of Chemical & Biotechnology (SCBT)
prnaren@scbt.sastra.edu
at
National Conference on Advances in Process Engineering
CAPE-2013
SASTRA University
Thanjavur, Tamilnadu 613 401 INDIA
19th October 2013
Progress Through Quality
Scilab – A Computing Tool for
Engineers

Why are we here?
• To learn about Scilab
– Syntax
– Advantages
– Limitation
• To master programming skills
• To become efficient programmer
19-Oct-13 Scilab - A Computing Tool for Engineers 2
Familiarize
programming tool
Scilab
and
complement our
learning process !

Outline
• What is Scilab ?
• Basics
– Variables, Matrices,
– Std. I/O function
• Linear algebra
• Functions and Subroutines
• Control / Looping statements
• ODE
• File operations and GUI
• Plot Functions

Scilab
• Computing tool
– Scripts / programming environment
– Mathematical operations
A place where we can compute / calculate !!!
Numerically solve equations
• Free and Open source
http://www.scilab.org
– Free to download
– Lot of help material available over net
http://help.scilab.org/docs/5.4.1/en_US/index.html

Familiarization
• Version 5.4.1
Console
Variable
List
Command
History
File
Browser

Basic Operators and Functions
• Operators : +, -, *, /, ^
• sqrt
• %e
• %i
• %pi
• log
– This is based on “e” -
Natural logarithm
• log10
• Colon “:” operator
• sin cos tan
– sind cosd tand
– asin acos atan
• factorial
• sum
• product
• Relational
– > >= < <= == ~= <>
• Logical
– & | ~

Variables
• No class/type definitions or declarations
-->a = 3;
-->a
a =
3.
-->a = "Workshop";
-->a
a =
Workshop

Matrices
• Every variable is n dimension in nature
– No need to specify the dimensions / length / size
h = [ 1 24 -5]
-->h = [1 24 -5]
h =
1. 24. - 5.
-->h = 1;
-->h(1,2) = 24;
-->h(1,3) = - 5;
-->h
h =
1. 24. - 5.
-->h = [1 24];
-->h(1,3) = - 5;
-->h
h =
1. 24. - 5.

Matrices Cont.
-->x = [2 -3 4; 5 10 24]
x =
2. - 3. 4.
5. 10. 24.
-->x = [2 -3 4];
-->x(2,:) = [5 10 24];
-->x
x =
2. - 3. 4.
5. 10. 24.
-->x(2,:) = [5 10 24];
-->x
x =
0. 0. 0.
5. 10. 24.
-->x(1,:)=[2 -3 4]
x =
2. - 3. 4.
5. 10. 24.

Script Files
• Script file
– .sce
– .sci
 e - executable i – functions
 e – main script files i - for functions or sub-rountines
• “//” comment a statement
– Good programing etiquettes !
• clc
• clear

Tutorials
• Tut1: Product of two nos.
• Tut2: Product of two nos. + user input
• Tut3: Matrix calculations based on user
choice
• Tut4: Matrix calculations based on user
choice with condition check
• Tut5: Spline curves
• Tut6: Building blocks
• Tut7: Equation of motion : v
• Tut8: Equation of motion: v and x
• Tut9: Roots of polynomial
• Tut10: Smart Input for Tut4
• Tut11: Write output into text file
• Tut12: Sum on n numbers
• Tut1: Print statements
• Tut2: Input function
• Tut3: Switch case
• Tut4: If then else
• Tut5: Plot functions
• Tut6: Function (Sub routines)
• Tut7: ODE function : I order
• Tut8: Simultaneous ODE : Two I order
• Tut9: Inbuilt function fsolve
• Tut10: GUI
• Tut11: File operations
• Tut12: For looping

Tutorial 1
Multiplication of two numbers (23.4 and 21) and get
their product
• Objective
– General programming structure
clear
clc
different sections in program
– Different options for output (result display on console)
disp
mprintf
Tutorial-1 Script File

Tutorial 2
Multiplication of two numbers (user input) and get their
product
• Objective
– input function
Obtain user input and then perform computation
 Makes program more generic
 reusable !!

Tutorial 3
Perform operations on matrix based on user choice
• Objective
– Control statement – “select – case – end”
Obtain two matrices from user
 Perform arithmetic operations on the matrices based on user
choice
– Add two matrix
– Matrix multiplication
– Element wise multiplication

Tutorial 4
with conditional check
• Objective
– Control statement – “if - then – else - end”
Obtain two matrices from user
 Perform arithmetic operations on the matrices based on user
choice
– Add two matrix / Matrix multiplication / Element wise multiplication
Check whether the user entered value is within bounds / range !!

Tutorial 5
Plot splines
• Objective
– Plot functions
Generate equi-spaced data (data range)
 Generate splines
– Smooth polynomial
Plot the generated spline to know its nature

Tutorial 6
Building Block
• Objective
– Use of sub-routines or functions
 Define function once and call it wherever required
 Given dimensions of unit building block how many blocks are
required to build a wall

Tutorial 7
Equation of motion : Velocity of a moving body under
constant linear acceleration
• Objective
– Solve first order ODE
 Equation of motion for a moving body under constant acceleration
Acceleration “a”
– Constant
– Variable
0 0
t t u u
 

Tutorial 8
Equation of motion : Velocity and Location of a moving
body under constant linear acceleration
• Objective
– Solve two first order ODE’s
 Equation of motion for a moving body under constant acceleration
Acceleration “a”
– Constant
– Variable
0 0
t t u u
 

Tutorial 9
Roots of Polynomial
• Objective
– To determine the roots of polynomial
 Find x such that f(x) = 0
 Quadratic equation
– Define f(x)
– Guess a value for xroot such that f (xroot) = 0
– Use in-built function fsolve to determine a actual root
Tutorial-9Script File
0 0
t t u u
 
2
0 1 2
f (x) a a x a x
  

Tutorial 10
! Obtain data in Smart Way !
• Objective
– Use of simple GUI function to obtain data
Avoids error previously encountered in Tutorial 4 !

Tutorial 11
Write output data into a file
• Objective
– Use file I/O commands and write result into a file
 Circular cross section pipe of known (given) diameter D
 Fluid of known density ( r ) and viscosity ( m ) flowing at specified
volumetric flow rate
 Compute Reynolds no.
 If Re <= 2100 Flow is laminar
2100 < Re <= 5000 Transition
Re > 5000 Turbulent
Tutorial11-File-operation.sce
Du
Re
r

m

Tutorial 12
Sum on N numbers
• Objective
– Use looping statement – For loop
 Determine the sum of N numbers
Tutorial12-File-operation.sce
N
i
i 1
S x

 

To Sum Up
• Scilab as computing tool for engineers
• Basic arithmetic operations
• Computing abilities in Scilab
• Generic programming etiquette
• Use Tutorials and Web documents
• Improvise, learn (re-learn / un-learn)
• Use Scilab to complement your engineering
education

Gratitude
• CAPE-2013
– For this wonderful opportunity
• PR Team for their registration spree !!
• Technical and Infra support team
• Audience

THANK YOU
A person who never made a mistake never tried
anything new
- Albert Einstein
- 1879 -1955
Entities must not be
multiplied beyond necessity
- William of Ockham
- 12th A.D.

Cape2013 scilab-workshop-19Oct13

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