4-point Gauss Quadrature with MATLAB

[stvoffutt]

Homework Statement

I need to evaluate a function using 4-point GQ.

Homework Equations

GQ theory

The Attempt at a Solution

I have got more of a programming issue in MATLAB. I am new to MATLAB. Actually this is for a numerical analysis course where we kind of learn MATLAB on the fly. First, I have 4 .m files to calculate the 4-point GQ which are listed below. Now, I have the program running for a specific function.m file and it calculates correctly. But I want to modify my existing GQ routine such that I can call any function.m file I want to. I think this is more of a syntax issue than anything. Since I have no experience with MATLAB any input or suggestions will be greatly appreciated.
.m files:

Main Program
function gauss_quadFULL(a,b,'integrand')
format longe;

%fhandle = @integrand;
reference_weights = [0.3478548 0.6521452 0.6521452 0.3478548];
reference_nodes = [-0.861136312 -0.339981044 0.3399810436 0.8611363116];
[New_weights, New_nodes] = gauss_quad(a,b,reference_weights,reference_nodes);
FourPoint_Gauss = guass_quadSUM('integrand',New_weights,New_nodes)

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%This function takes the reference weights/nodes and transforms them to the [-1,1] interval

function [weights, nodes] = gauss_quad(a,b,reference_weights,reference_node)

weights=1/2*(b-a)*reference_weights;
nodes = 1/2*((b-a)*reference_node+(b+a));
[weights, nodes]

---------------------------------------------------------------------------------------------
%Does the sum for GQ using nodes and weights

function result = guass_quadSUM(fhandle,New_weights,New_nodes)

result = 0;
nn = length(New_weights); % We choose weights here instead of nodes because
% in multidemensions nodes is a matrix.
for j=1:nn
result = result + New_weights(j)*feval(fhandle,New_nodes(j));
end

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%example function
function result = function_f_quad(x)

result = cos(pi/4*x)/sin(pi/4*x)^2;

---------------------------------------------------------------------------------------------

When I call the main function I get the following error:

EDU>> gauss_quadFULL(0,1,function_f_quad)
Error using function_f_quad (line 3)
Not enough input arguments.


Again, if I replace the loop sum by:
result = result + New_weights(j)*function_f_quad(New_nodes(j));
I get the correct answer. My question is how to pass the GQ main routine a new function, say f1.m, that does the same thing but for any function that I have in an .m file? I have tried messing with the handles and single quotes but I keep getting the same error in my program. Please help. Thank you in advance.

 

[stvoffutt]

I figured it out. Thanks.