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add a stretched Kubo-Toyabe function to the PTheory class, including an update of the docu. Motivated by Z. Salman, which also provided a patch, which needed some improvements.

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suter_a
2013-09-10 09:03:21 +00:00
parent e1d99a07cb
commit 3443820e83
18 changed files with 311 additions and 182 deletions
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63
src/classes/PTheory.cpp
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@ -444,6 +444,10 @@ Double_t PTheory::Func(register Double_t t, const PDoubleVector& paramValues, co
return CombiLGKT(t, paramValues, funcValues) * fMul->Func(t, paramValues, funcValues) +
fAdd->Func(t, paramValues, funcValues);
break;
case THEORY_STR_KT:
return StrKT(t, paramValues, funcValues) * fMul->Func(t, paramValues, funcValues) +
fAdd->Func(t, paramValues, funcValues);
break;
case THEORY_SPIN_GLASS:
return SpinGlass(t, paramValues, funcValues) * fMul->Func(t, paramValues, funcValues) +
fAdd->Func(t, paramValues, funcValues);
@ -543,6 +547,9 @@ Double_t PTheory::Func(register Double_t t, const PDoubleVector& paramValues, co
case THEORY_COMBI_LGKT:
return CombiLGKT(t, paramValues, funcValues) * fMul->Func(t, paramValues, funcValues);
break;
case THEORY_STR_KT:
return StrKT(t, paramValues, funcValues) * fMul->Func(t, paramValues, funcValues);
break;
case THEORY_SPIN_GLASS:
return SpinGlass(t, paramValues, funcValues) * fMul->Func(t, paramValues, funcValues);
break;
@ -630,6 +637,9 @@ Double_t PTheory::Func(register Double_t t, const PDoubleVector& paramValues, co
case THEORY_COMBI_LGKT:
return CombiLGKT(t, paramValues, funcValues) + fAdd->Func(t, paramValues, funcValues);
break;
case THEORY_STR_KT:
return StrKT(t, paramValues, funcValues) + fAdd->Func(t, paramValues, funcValues);
break;
case THEORY_SPIN_GLASS:
return SpinGlass(t, paramValues, funcValues) + fAdd->Func(t, paramValues, funcValues);
break;
@ -715,6 +725,9 @@ Double_t PTheory::Func(register Double_t t, const PDoubleVector& paramValues, co
case THEORY_COMBI_LGKT:
return CombiLGKT(t, paramValues, funcValues);
break;
case THEORY_STR_KT:
return StrKT(t, paramValues, funcValues);
break;
case THEORY_SPIN_GLASS:
return SpinGlass(t, paramValues, funcValues);
break;
@ -1752,6 +1765,56 @@ Double_t PTheory::CombiLGKT(register Double_t t, const PDoubleVector& paramValue
(1.0 + 2.0*(1.0-lambdaL_t-lambdaG_t_2)*TMath::Exp(-(lambdaL_t+0.5*lambdaG_t_2)));
}
//--------------------------------------------------------------------------
/**
* <p> theory function: stretched Kubo-Toyabe in zero field.
* Ref: Crook M. R. and Cywinski R., J. Phys. Condens. Matter, 9 (1997) 1149.
*
* \f[ = 1/3 + 2/3 \left(1-(\sigma t)^\beta \right) \exp\left(-(\sigma t)^\beta / \beta\right)\f]
* or the time shifted version of it.
*
* <b>meaning of paramValues:</b> \f$\sigma\f$, \f$\beta\f$ [, \f$t_{\rm shift}\f$]
*
* <b>return:</b> function value
*
* \param t time in \f$(\mu\mathrm{s})\f$, or x-axis value for non-muSR fit
* \param paramValues parameter values
* \param funcValues vector with the functions (i.e. functions of the parameters)
*/
Double_t PTheory::StrKT(register Double_t t, const PDoubleVector& paramValues, const PDoubleVector& funcValues) const
{
// expected parameters: sigma beta [tshift]
Double_t val[3];
assert(fParamNo.size() <= 3);
// check if FUNCTIONS are used
for (UInt_t i=0; i<fParamNo.size(); i++) {
if (fParamNo[i] < MSR_PARAM_FUN_OFFSET) { // parameter or resolved map
val[i] = paramValues[fParamNo[i]];
} else { // function
val[i] = funcValues[fParamNo[i]-MSR_PARAM_FUN_OFFSET];
}
}
// check for beta too small (beta < 0.1) in which case numerical problems could arise and the function is anyhow
// almost identical to a constant of 1/3.
if (val[1] < 0.1)
return 0.333333333333333;
Double_t tt;
if (fParamNo.size() == 2) // no tshift
tt = t;
else // tshift present
tt = t-val[2];
Double_t sigma_t = TMath::Power(tt*val[0],val[1]);
return 0.333333333333333 *
(1.0 + 2.0*(1.0-sigma_t)*TMath::Exp(-sigma_t/val[1]));
}
//--------------------------------------------------------------------------
/**
* <p> theory function: spin glass function