# Evaluate the following triple integral using single applications of Simpson’s 1/3 rule.

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Moon Shadow on 29 Nov 2016
Commented: Moon Shadow on 29 Nov 2016
Evaluate the following triple integral using single applications of Simpson’s 1/3 rule. I have all the code for this question but I am getting error: Undefined function or variable 'simpson'. How to fix this error or add the 'simpson' function.
x1 = [-3:0.01:1];
fx1 = (x1).^2;
a= simpson(x1,fx1 , [],'1/3');
y1 = [0:0.01:2];
fy1 = ones(length(y1),1);
b= simpson(y1,fy1 , [],'1/3');
z1 = [-2:0.01:2];
fz1 = ones(length(z1),1);
c= simpson(z1,fz1 , [],'1/3');
I1 =a*b*c;
x2 = [-3:0.01:1];
fx2 = ones(length(x2),1);
aa= simpson(x2,fx2 , [],'1/3');
y2= [0:0.01:2];
fy2 = y2;
bb= simpson(y2,fy2 , [],'1/3');
z2 = [-2:0.01:2];
fz2 = z2;
cc= simpson(z2,fz2 , [],'1/3');
I2=aa*bb*cc;

KSSV on 29 Nov 2016
There is no inbuilt function named simpson in matlab. You may check quad inbuilt function or download the file from the exchange.
Moon Shadow on 29 Nov 2016
What about simps function? I also get: Undefined function or variable 'simps'.
Moon Shadow on 29 Nov 2016
Here Simpson function https://www.mathworks.com/matlabcentral/fileexchange/28726-simpson-s-rule-integration/content/simpsons.m

Moon Shadow on 29 Nov 2016
How to use file from the exchange in the matlab? I want to use simps function.
KSSV on 29 Nov 2016
Download the file, copy in a folder, read the documentation part of the file, see how to input and then use. Mostly they give an example on how to run. First run the code for example case.