Help with code: Matlab code not printing last verification line.

I can't get Matlab to print the last "data within tolerance" line:

function [integral] = intmidpoint(N)
clear
clc
%INTMIDPOINT numerical integration using the composite midpoint rule
    clc
%define the integration limits
    a=0;
    b=2;
    %this is the aim of absolute error required
aim = 0.001;

%define the number of sub-intervals to be used
    if nargin == 1
        n=N;
    else
        n=1;
    end
    h=(b-a)/n;
%approximate integral using the composite mid-point rule
      integral=0.0;
%add the contribution of each sub-interval in turn

abs_err = realmax;
while abs_err>aim;
        h=(b-a)/n;
    integral=0.0;
     for i=1:n;
        x_left = a+(i-1)*h;
        x_right = a+i*h;
        x_half = (x_left+x_right)/2.0;
        f_half = f(x_half);
        integral = integral+h*f_half;
        abs_err=abs(4-integral);

       end;
       fprintf('2 Midpoint approximation to integral using %g subintervals is %g.  \n Data outside of tolerance.  Abosolute error is %g, which is greater than 0.001. Increase the number of steps.  \n',n,integral,abs_err);
       n = n + 1; 
      if abs_err>aim;
          continue;
     fprintf('test Midpoint approximation to integral using %g subintervals is %g.  \n Data within tolerance.  Absolute error is %g, which is less than 0.001. \n',n,integral,abs_err);        
      end;

end;
end

%subfunction defines the integrand
function [f_value] = f(x)
    f_value = (x)^3;

end

Answer 1

[Walter Roberson]

The "continue" is going to be executed before the fprintf() that is in the same "if"

[Tyw7]

I tried moving it before but it adds one extra line to the output rather than terminating.

[Tyw7]

2 Midpoint approximation to integral using 43 subintervals is 3.99892.  
 Data outside of tolerance.  Abosolute error is 0.00108167, which is greater than 0.001. Increase the number of steps.  
test Midpoint approximation to integral using 44 subintervals is 3.99892.  
 Data within tolerance.  Absolute error is 0.00108167, which is less than 0.001. 
2 Midpoint approximation to integral using 44 subintervals is 3.99897.  
 Data outside of tolerance.  Abosolute error is 0.00103306, which is greater than 0.001. Increase the number of steps.  
test Midpoint approximation to integral using 45 subintervals is 3.99897.  
 Data within tolerance.  Absolute error is 0.00103306, which is less than 0.001. 
2 Midpoint approximation to integral using 45 subintervals is 3.99901.  
 Data outside of tolerance.  Abosolute error is 0.000987654, which is greater than 0.001. Increase the number of steps.  

ans =

      3.9990

>>

[Walter Roberson]

You want break rather than continue

[Geoff Hayes]

Try this

 if abs_err>aim
     fprintf('test Midpoint approximation to integral using %g subintervals is %g.  \n Data within tolerance.  Absolute error is %g, which is less than 0.001. \n',n,integral,abs_err); 
     break;       
 end

Note that the

 ans =
      3.9990

is the output parameter returned from your function call. You are probably calling your function from the command line without assigning the output to a variable. Try calling your function as

 [estIntegral] = intmidpoint(42);

to suppress the extra output. (Note that it is the use of the semi-colon that is suppressing the output.)