problem about inner product of function

Frist, Thanks for your attention for my question, the following is my code:

    % code
function responsenum = numreponse(num)
switch num
      case 1
           response = @(x,y)x+y;
      case 2
           response = @(x,y)x*y;
function y = innerprod(fun1,fun2)
         y = fun1.*fun2;
psi = dblquad(innerprod(numreponse(1),numreponse(2)),-1,1,-1,1,1e-2,@quad1)

when i run the code, the error message is "undefined function 'times' for input arguments of type 'function_handle'" . i will be appreciated if you can give me a help!ThKs

Answer 1

[Walter Roberson]

function y = innerprod(fun1,fun2)
       y = @(x,y) fun1(x,y) .* fun2(x,y);

[Chongqing Fan]

Dear Walter,

Thank you so much for your answer, it works! when the fun1 and fun2 is constant, this code is not work, could you give me some advice, why the below question occurs because i can not fully understand the principle of the MATLAB, could you give me some recommendation or books or website to improve my matlab skill!

All the best,

Chongqing Fan

[Walter Roberson]

function y = innerprod(fun1,fun2)
  if isa(fun1, 'function_handle')
    if isa(fun2, 'function_handle')
      y = @(x,y) fun1(x,y) .* fun2(x,y);
    else
      y = @(x,y) fun1(x,y) .* fun2;
    end
  elseif isa(fun2, 'function_handle')
    y = @(x,y) fun1 .* fun2(x,y);
  else
    y = @(x,y) fun1 .* fun2;
  end