Question regards double integral

Hey I have a problem with double integral

this is my function

xmin=0;

xmax=1;

ymin=0;

ymax=x;

ymin<y<ymax;

xmin<x<xmax

F=((y^3)/(x^2+y^2));

a=integral2(F,ymin,ymax,xmin,xmax);

But there seems to be a problem with ymax, I keep getting an error saying undefined function or variable of x

ymax=x

By the way, I want to integrate y first then x

Answer 1

[Roger Stafford]

Writing "ymax=x;" doesn't do the job. If 'ymax' is not a scalar value, it needs to be a 'function handle'. The same applies to the integrand function "F=((y^3)/(x^2+y^2));".

Note also that your integration limits are in backwards order. To integrate w.r. y first and then x, you need to write:

a=integral2(F,xmin,xmax,ymin,ymax);

That is the way 'integral2' is defined.

You can read about these requirements at:

http://www.mathworks.com/help/matlab/ref/integral2.html

and function handles at:

http://www.mathworks.com/help/matlab/function-handles.html