Thread: Please correct the program

Can somebody please correct my MATLAB program. I am new to matlab and I am taking a course (not matlab) where it requires some matlab.

the code below should return answer of integral...

Code:

% MATLAB Codes for GAUSS QUADRATURE
% Shakil Ahmed
clear all
p=4; %Degree of Polynomial
n=(p+1)/2; %To find number of Gauss points, ngp
ngp=round(n)
b=4; %Upper Limit
a=0; %Lower Limit
J=(b-a)/2; %Jacobian
% get gauss points in the parent element domain [-1, 1] and the corresponding weights
% function [w,gp] = gauss(ngp)
if (ngp == 1)
  gp= 0;
  w= 2;
  for nn=1:ngp
    x=((a+b)/2)+(gp(nn)*((b-a)/2))
    %f(nn)=(x^2+1); %Problem 4.6(a)
    % ANSWER IS 25.333
    f(nn)=(x^4 + 2*x^2); %Problem 4.6(b)
    %ANSWER IS 1.73333
    I=[I J*w*f]
    A=sum(I)
   if (ngp == 2)
     gp = [-0.57735027, 0.57735027];
     w = [1, 1];
     for nn=1:ngp
       x=((a+b)/2)+(gp(nn)*((b-a)/2))
       %f(nn)=(x^2+1); %Problem 4.6(a)
       % ANSWER IS 25.333
       f(nn)=(x^4 + 2*x^2); %Problem 4.6(b)
       %ANSWER IS 1.73333
       I=[I J*w*f]
       A=sum(I)
       if (ngp == 3)
         gp = [-0.7745966692, 0.7745966692, 0.0];
         w = [0.5555555556, 0.5555555556, 0.8888888889];
         for nn=1:ngp
           x=((a+b)/2)+(gp(nn)*((b-a)/2))
           %f(nn)=(x^2+1); %Problem 4.6(a)
           % ANSWER IS 25.333
           f(nn)=(x^4 + 2*x^2); %Problem 4.6(b)
           %ANSWER IS 1.73333
           I=[I J*w*f]
           A=sum(I)
         end
       end
     end

Originally Posted by shakil

Can somebody please correct my MATLAB program. I am new to matlab and I am taking a course (not matlab) where it requires some matlab.

the code below should return answer of integral...

Code:

% MATLAB Codes for GAUSS QUADRATURE
% Shakil Ahmed
clear all
p=4; %Degree of Polynomial
n=(p+1)/2; %To find number of Gauss points, ngp
ngp=round(n)
b=4; %Upper Limit
a=0; %Lower Limit
J=(b-a)/2; %Jacobian
% get gauss points in the parent element domain [-1, 1] and the corresponding weights
% function [w,gp] = gauss(ngp)
if (ngp == 1)
  gp= 0;
  w= 2;
  for nn=1:ngp
    x=((a+b)/2)+(gp(nn)*((b-a)/2))
    %f(nn)=(x^2+1); %Problem 4.6(a)
    % ANSWER IS 25.333
    f(nn)=(x^4 + 2*x^2); %Problem 4.6(b)
    %ANSWER IS 1.73333
    I=[I J*w*f]
    A=sum(I)
   if (ngp == 2)
     gp = [-0.57735027, 0.57735027];
     w = [1, 1];
     for nn=1:ngp
       x=((a+b)/2)+(gp(nn)*((b-a)/2))
       %f(nn)=(x^2+1); %Problem 4.6(a)
       % ANSWER IS 25.333
       f(nn)=(x^4 + 2*x^2); %Problem 4.6(b)
       %ANSWER IS 1.73333
       I=[I J*w*f]
       A=sum(I)
       if (ngp == 3)
         gp = [-0.7745966692, 0.7745966692, 0.0];
         w = [0.5555555556, 0.5555555556, 0.8888888889];
         for nn=1:ngp
           x=((a+b)/2)+(gp(nn)*((b-a)/2))
           %f(nn)=(x^2+1); %Problem 4.6(a)
           % ANSWER IS 25.333
           f(nn)=(x^4 + 2*x^2); %Problem 4.6(b)
           %ANSWER IS 1.73333
           I=[I J*w*f]
           A=sum(I)
         end
       end
     end

First close all the blocks opened by "if" or "for".

Then try executing the code in the debugger.

CB