dblquad function handle help

Hello. I'm facing the following problem:

dblquad('power(x,3)*power(y,3)',0,1,0,1)

Works perfectly fine! But...

dblquad('x^3*y^3',0,1,0,1)

Gives the following error...

Error using inlineeval (line 15)
Error in inline expression ==> x^3*y^3
 Inputs must be a scalar and a square matrix.
To compute elementwise POWER, use POWER (.^) instead.

Error in inline/subsref (line 24)
    INLINE_OUT_ = inlineeval(INLINE_INPUTS_, INLINE_OBJ_.inputExpr, INLINE_OBJ_.expr);

Error in quad (line 72)
y = f(x, varargin{:});

Error in dblquad>innerintegral (line 82)
    Q(i) = quadf(intfcn, xmin, xmax, tol, trace, y(i), varargin{:});

Error in quad (line 72)
y = f(x, varargin{:});

Error in dblquad (line 58)
Q = quadf(@innerintegral, ymin, ymax, tol, trace, intfcn, ...

So, what I've tried is:

dblquad('x.^3*y.^3',0,1,0,1)

And it works perfectly well. The real problem is that I must define a vector with functions:

k=1;
syms x y
for i=1:n;
      for j=1:n;
          f(k)=power(x,1+i)*power(y,1+j);
          k=k+1;
      end  
end

And then I must deliver the following code to dblquad:

dblquad(char(f(k)),0,1,0,1);

And char(f(k)) gives me 'x^(1+i)*y^(j+1)' form, which dblquad can't handle. (Noting that "i" and "j" are now real numbers, arbitrary.)

Any ideas?

Answer 1

[Walter Roberson]

char() isn't going to give you that unless you are using the symbolic toolbox. If you are, see matlabFunction()

Also see vectorize()

Passing strings in instead of function handles is no longer recommended.

[Cyberz]

Is there a way in which I could write my functions as a real function handles?

The functions I need to define are the same as in the question.

[Cyberz]

Yay

Vectorize works perfectly fine! ;)

dblquad(vectorize(f(k)),0,1,0,1);

Thank you!