# HOW DO I DO THAT IN MATLAB SERIES?

In this series, I am answering questions that students have asked me about MATLAB. Most of the questions relate to a mathematical procedure.

## TOPIC

How do I integrate a continuous function?

## SUMMARY

```% Language : Matlab 2008a;
% Authors : Autar Kaw;
% Mfile available at
% http://numericalmethods.eng.usf.edu/blog/integration.m;
% Last Revised : March 28, 2009;
% Abstract: This program shows you how to integrate a given function.
clc
clear all
```

## INTRODUCTION

```disp('ABSTRACT')
disp('   This program shows you how to integrate')
disp('   a given function')
disp(' ')
disp('AUTHOR')
disp('   Autar K Kaw of http://autarkaw.wordpress.com')
disp(' ')
disp('MFILE SOURCE')
disp('   http://numericalmethods.eng.usf.edu/blog/integration.m')
disp(' ')
disp('LAST REVISED')
disp('   March 29, 2009')
disp(' ')
```
```ABSTRACT
This program shows you how to integrate
a given function

AUTHOR
Autar K Kaw of http://autarkaw.wordpress.com

MFILE SOURCE
http://numericalmethods.eng.usf.edu/blog/integration.m

LAST REVISED
March 29, 2009

```

## INPUTS

```% Integrate exp(x)*sin(3*x) from x=2.0 to 8.7
% Define x as a symbol
syms x
% Assigning the function to be differentiated
y=exp(x)*sin(3*x);
% Assigning the lower limit
a=2.0;
% Assigning the upper limit
b=8.7;
```

## DISPLAYING INPUTS

```disp('INPUTS')
func=['  The function is to be integrated is ' char(y)];
disp(func)
fprintf('  Lower limit of integration, a= %g',a)
fprintf('\n  Upper limit of integration, b= %g',b)
disp('  ')
disp('  ')
```
```INPUTS
The function is to be integrated is exp(x)*sin(3*x)
Lower limit of integration, a= 2
Upper limit of integration, b= 8.7

```

## THE CODE

```% Finding the integral using the int command
% Argument 1 is the function to be integrated
% Argument 2 is the variable with respect to which the
%    function is to be integrated - the dummy variable
% Argument 3 is the lower limit of integration
% Argument 4 is the upper imit of integration
intvalue=int(y,x,a,b);
intvalue=double(intvalue);
```

## DISPLAYING OUTPUTS

```disp('OUTPUTS')
fprintf('  Value of integral is = %g',intvalue)
disp('  ')
```
```OUTPUTS
Value of integral is = -525.527
```