Solving Problem in Fortran Program - Bevington Polyfit.f

[akila]

hi all,

greetings,
i have a fortran prg to fit 2nd order polynomial to my data
taken from (bevington--- polfit.f)

i'm making some mistake, and i could not find what is the problem with this.
When i give some other other random data it is fitting properly
but not the data i have :(
for y = a + bx + cx^2 i should get the coefficients to be

a = 1.4558380406304288E+03
b = -3.6779173737460803E+02
c = 2.3247378080674739E+01

but I am getting as
a = -16.2156696
b = -1.78127503
c = 0.496948689


can somebody please please help me to find out the problem

here i have attached the prg

thank you,
regards,
akila

 

[minger]

Firstly, you can enclose code directly into the forum by using the CODE tags.

OK, what compiler options have you used? I notice that you don't include an IMPLICIT NONE statement. wt is not defined as an array, how does the implicit declaration work for arrays?

If you got polfit from some sort of library, then your inputs are probably wrong. Also, go back to that library's documentation and make sure you know what all those variables are. For example, the variable MODE in the subroutine isn't crystal clear to me.

 

[quicknote]

Hello Akila,

Thank you for reaching out for help with your Fortran program. It sounds like you are trying to fit a 2nd order polynomial to your data using the Bevington method. I understand that you are experiencing some difficulties with the program and are not getting the expected results.

Firstly, it is important to make sure that your data is properly formatted and in the correct units for the program to work correctly. Double check that your data is in the same format as the example data in the Bevington method and that the units are consistent. This could be a common mistake that can cause incorrect results.

Another possibility is that there may be a mistake in the code itself. I would recommend going through the program line by line and double checking each step to ensure that it is performing the intended function. It may also be helpful to compare your code to other examples of the Bevington method to see if there are any differences or missing steps.

If you are still having trouble finding the issue, it may be helpful to seek out a colleague or fellow programmer who is familiar with Fortran to review your code and provide some insight. It can also be helpful to take a break and come back to the problem with fresh eyes. Sometimes a new perspective can help identify the problem.

I hope this helps and that you are able to successfully solve the problem with your Fortran program. Best of luck to you.

Sincerely,