#!/usr/local/bin/perl
#This is a perl script for trapizoidal approximation.
#Unless you konw something about perl script, you will need some help.
#To run this program, save it as trapiz.pl (or as any dot-pl file).  
#You will change the function in ourFunction sub-program.
# a is lower limit, b is upper limit and n is the number of subinterval. 
$a = 0;
$b= 2;
$n=8;
$delX = ($b - $a)/$n; 
$z=$a;
$y= ourFunction($z);
$sum =$y; 

for($i=0; $i<$n-1; $i++) {

$z= $z+$delX;
$y= ourFunction($z);
$sum=$sum+2*$y; 

} 


$z= $z+$delX;
$y= ourFunction($z);
$sum=$sum+$y;

$int= .5*$delX*$sum; 


print " \n int =  $int \n "; 

sub ourFunction {
local ($x); 
$x = @_[0];
#$f= sqrt(1+$x*$x*$x); 
$f=1/(3**($x*$x));
print " x=$x  and f= $f \n "; 

return $f;
}