Re: MultiDimFit Print method.

Hello all,

After looking at CVS head, i think that the change (printing p-1 instead of p) is needed also for kMononomials (The example results i sent were from a fit using monomials).

Marcos

> This is now fixed in the CVS head.
> Thanks for this report.
>
> Rene Brun
>
> On Tue, 12 Jul 2005, Christian Holm
> Christensen wrote:
>
>> Hi Marcos,
>>
>> On Mon, 2005-07-11 at 20:48 +0200, Marcos Gimenez wrote:
>>> Hello all
>>>
>>> After making a succesfull fit using the MultiDimFit class, i printed
>>> the output function using fit->Print("m"); and i found that there
>>> were diferences in the powers shown between fit->Print("m") and
>>> fit->Print("c");
>>>
>>>
>>> Using Print("m") (bad results after testing the fit)
>>>
>>> Parameterization:
>>> -----------------
>>> Normalised variables:
>>> y_0 = 1 + 2 * (x_0 - 1) / (1 - -1)
>>> y_1 = 1 + 2 * (x_1 - 1) / (1 - -1)
>>>
>>> f(y_0, y_1) = 0.6374
>>> + 28.69 * y_0
>>> - 0.4414 * y_0^3
>>> + 0.005439 * y_0 * y_1^3
>>> + 14.73 * y_0^4
>>> + 19.87 * y_1^5
>>> + 0.5973 * y_0^3 * y_1^3
>>> - 0.1731 * y_0^5
>>> - 22.42 * y_0^6
>>> - 17.31 * y_1^7
>>> + 0.2964 * y_1
>>> - 3.186 * y_1^3
>>> - 0.2975 * y_1^4
>>>
>>>
>>>
>>> Using Print("c") (good results after testing the fit, same results
>>> when using fit->Eval(x) method)
>>>
>>> Coefficients:
>>> -------------
>>> # Value Error Powers
>>> ---------------------------------------
>>> 0 0.6374 0.3363 0 0
>>> 1 28.69 1.419 1 0
>>> 2 -0.4414 2.462 2 0
>>> 3 0.005439 0.8616 1 2
>>> 4 14.73 10.56 3 0
>>> 5 19.87 75.6 0 4
>>> 6 0.5973 1.171 2 2
>>> 7 -0.1731 2.452 4 0
>>> 8 -22.42 9.288 5 0
>>> 9 -17.31 65.37 0 6
>>> 10 0.2964 0.63 0 1
>>> 11 -3.186 10.77 0 2
>>> 12 -0.2975 0.7781 0 3
>>>
>>> If i look in the TMultiDimFit source and i search what it does when
>>> "m" option it is selected there is a part in the code after the
>>> switch(fPolyType) that i think it should be using p-1 instead of p,
>>> because TMultiDimFit stores power+1.
>>>
>>> Now
>>>
>>> for (Int_t j = 0; j < fNVariables; j++) {
>>> Int_t p = fPowers[fPowerIndex[i] * fNVariables + j];
>>> switch (p) {
>>> case 1: break;
>>> case 2: cout << " * y_" << j; break;
>>> default:
>>> switch(fPolyType) {
>>> case kLegendre: cout << " * L_" << p << "(y_" << j << ")";
>>> break; case kChebyshev: cout << " * C_" << p << "(y_" << j
>>> << ")"; break; default: cout << " * y_" << j << "^"
>>> << p; break; }
>>> }
>>>
>>> }
>>>
>>> I think it should be
>>>
>>> for (Int_t j = 0; j < fNVariables; j++) {
>>> Int_t p = fPowers[fPowerIndex[i] * fNVariables + j];
>>> switch (p) {
>>> case 1: break;
>>> case 2: cout << " * y_" << j; break;
>>> default:
>>> switch(fPolyType) {
>>> case kLegendre: cout << " * L_" << p-1 << "(y_" << j <<
>>> ")"; break; case kChebyshev: cout << " * C_" << p-1 <<
>>> "(y_" << j << ")"; break; default: cout << " * y_"
>>> << j << "^" << p-1; break; }
>>> }
>>>
>>> }
>>>
>>
>> You are right. TMultiDimFit stores the powers as `p+1', rather than
>> `p', so you are right - the Print method, under option `m', one (1)
>> should be subtracted from `p' to get the right result.
>>
>> Rene, will you fix it? Thanks.
>>
>> Yours,
Received on Tue Jul 19 2005 - 09:14:37 MEST