winsert
September 19, 2006, 8:38am
#1
i have a fit of 30 parameter, do everyone know how to improve the resule?

i found in my combine fit function , the different sequence of the sub-function can get different result!
for example:

```
Double_t fit_f( Double_t *x, Double_t *par)
{
Double_t fitval=fit_3+fit_1+fit_2;
//different with Double_t fitval=fit_2+it_3fit_1;
return fitval;
}
```

`f->Fit("fit","LEV+");`

is in use.

brun
September 19, 2006, 1:12pm
#2
Could you post the shortest possible running version of your script explaining what you are doing. No way to give you more hints
without looking at your problem.

Rene

winsert
September 19, 2006, 2:01pm
#3
hi brun,
i attatch you the code .
i have describe the problem in the code file.
all_diff_data.txt (3.39 KB)
fit2Dg_of_diff.c (4.16 KB)

brun
September 20, 2006, 6:41am
#4
Two problems:
-you must include

```
#include <Math/SpecFuncMathCore.h>
```

-the prototype for assoc_legendre is

```
double assoc_legendre(unsigned l, unsigned m, double x)
```

ie you have a missing argument in your code

Rene