2D trapezoidal rule

Calculates a double integral using trapezoidal rule.

Description

This is a very simple program that makes use of Matlab's trapz (single integral). It has the benefit that it can be used to integrate over vectors x, y, and the function f(x,y), rather than on lower and upper limits. It can also be used with nonuniform spacing at the input vectors.

Example of nonuniform spacing:
x=[0,.1,.3,.45,.6,.8,.99,1]
y=[0,.05,.1,.2,.7,.57,.92,1]

Acknowledgements

This file inspired 3 D Trapezoidal Rule.

• Required Products: MATLAB
• MATLAB release: MATLAB 7.1.0 (R14SP3)

[Mohammed Sadeq Al-Rawi]

Yes, that's a nice statement. But, I think it should be (according to the latest change)

result = trapz(y,trapz(x,mat,1),2);

Although I think keeping it as is is more illustrative. I will add it as a comment.

Thanks for the comment.
N.B. I am still not sure if it would perform faster/better than quad2d if one use it with empirical data.

[Richard Crozier]

Could be replaced with a single line:

result = trapz(x,trapz(y,mat,1),2);