Converting Matlab to C Code

The following code is the Matlab version which works perfectly:

Starting=[1 1 -1];
options=optimset('Display','iter');
Estimates=fminsearch(@myfit,Starting,options,t_d,Data)  

    function sse=myfit(params,Input,Actual_Output)
    a=params(1);
    b=params(2);
    c=params(3);

Calling the Function:

    Fitted_Curve = (1/(a*b))*(c-asinh(sinh(c)*exp(a*Input*2*pi)));
    Error_Vector=Actual_Output-Fitted_Curve ;
    sse=sum(Error_Vector.^2);

I have tried to replicate the function in C which looks like this:

static double function(int n, double x[])
{
  double c;
    double Fitted_Curve[5];
    double Error_Vector[5];
    int i;
    double a, b, sum = 0;
    double  v1[5], v2[5], geom_inv[5], norm = 0, norm_2 = 0, v2sum = 0, x_coeff = 0;
//    Actual_Output[5] = {1.2, 2.693, 4.325, 6.131, 8.125};

a = x[0];
b=x[1];
c=x[2];

    for (i = 0; i <= 4; i++)
    {

      Fitted_Curve[i] = (1/(a*b))*(c-asinh(sinh(c)*exp(a*Input[i]*2*pi)));

      Error_Vector[i] = Actual_Output[i]-Fitted_Curve[i];
      }

      for (i = 0; i <= 4; i++)
      {
          sum = sum + Error_Vector[i]*Error_Vector[i];
      }
      printf("sum = %f\n", sum);
      a_global = a;
      b_global = b;
     // x_coeff_global = x_coeff;
      return sum;

}

It runs but doesnt get the same result as the Matlab. The matlab is right, I know that, but the C doesnt get close enough

Answer 1

[Walter Roberson]

Your MATLAB code is not right. We discussed this before here. You have too many inputs to "myfit"

[Alex]

The Matlab works and it produces the correct values to 3dp. I'm not sure what you are spotting that I am not but I think you may be getting confused with the fact that it is sent first to the function fminsearch which then send myfit the correct information, because it works