Numerical integration using Trapz

9 views (last 30 days)
Hi all,
I am trying to calculate a double integral over a rectangular grid using trapz.
The grid is defined as:
[x,z] = meshgrid(xp,zp);
xp and zp are the 1d arrays of x and z coordinates of the grid.
I trying to calculate the function values (F) at the grid nodes as:
F(i,j)=trapz(zp,trapz(xp,g.*f,2));
here,
g is a function of x and z i.e. g(x,z) whereas, f values are already calculated values at each node of the grid i.e. not a function of x and z.
Can someone suggest how may I do it, please.

Accepted Answer

Star Strider
Star Strider on 6 May 2021
That should produce one scalar value as ‘F’, so the subscripts are not necessary.
I would do something like this —
F = trapz(zp,trapz(xp,g.*f));
The result of the first trapz call will be a vector, and of the second will be a scalar. So long as ‘g’ and ‘f’ have compatible dimensions, and they match ‘xp’ and ‘zp’ appropriately, that should work.
  6 Comments
Star Strider
Star Strider on 7 May 2021
As always, my pleasure!

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by