source: sans/Analysis/trunk/Put in User Procedures/SANS_Models_v3.00/Power_Law_model.ipf @ 42

#pragma rtGlobals=1             // Use modern global access method.
////////////////////////////////////////////////////
//      J. Barker, 2-10-99
//////////////////////////////////
Proc PlotPower_Law(num,qmin,qmax)
        Variable num=512, qmin=.001, qmax=.2
        Prompt num "Enter number of data points for model: "
        Prompt qmin "Enter minimum q-value (^1) for model: " 
         Prompt qmax "Enter maximum q-value (^1) for model: "
//
        Make/O/D/n=(num) xwave_Power_Law, ywave_Power_Law
        xwave_Power_Law =  alog(log(qmin) + x*((log(qmax)-log(qmin))/num))
        Make/O/D coef_Power_Law = {1e-6, 4.0, 1.0}
        make/o/t parameters_Power_Law = {"Coefficient, A ", "(-)Power","Incoherent Bgd (cm-1)"}
        Edit parameters_Power_Law, coef_Power_Law
        ywave_Power_Law  := Power_Law_Model(coef_Power_Law, xwave_Power_Law)
        Display ywave_Power_Law vs xwave_Power_Law
        ModifyGraph marker=29, msize=2, mode=4
        ModifyGraph log(left)=1
        ModifyGraph log(bottom)=1
        Label bottom "q (\\S-1\\M) "
        Label left "Power-Law (cm\\S-1\\M)"
        AutoPositionWindow/M=1/R=$(WinName(0,1)) $WinName(0,2)
//
End
////////////////////////////////////////////////////
Proc PlotSmearedPower_Law()                                                             // Power-Law
        //no input parameters necessary, it MUST use the experimental q-values
        // from the experimental data read in from an AVE/QSIG data file
        
        // if no gQvals wave, data must not have been loaded => abort
        if(ResolutionWavesMissing())
                Abort
        endif
        
        // Setup parameter table for model function
        Make/O/D smear_coef_Power_Law = {1e-6, 4.0, 1.0}
        make/o/t smear_parameters_Power_Law = {"Coefficient, A ", "(-)Power","Incoherent Bgd (cm-1)"}
        Edit smear_parameters_Power_Law,smear_coef_Power_Law                                    //display parameters in a table
        
        // output smeared intensity wave, dimensions are identical to experimental QSIG values
        // make extra copy of experimental q-values for easy plotting
        Duplicate/O $gQvals smeared_Power_Law,smeared_qvals                             //
        SetScale d,0,0,"1/cm",smeared_Power_Law                                                 //

        smeared_Power_Law := SmearedPower_Law_Model(smear_coef_Power_Law,$gQvals)               // SMEARED function name
        Display smeared_Power_Law vs smeared_qvals                                                                      //
        ModifyGraph log=1,marker=29,msize=2,mode=4
        Label bottom "q (\\S-1\\M)"
        Label left "Power_Law (cm\\S-1\\M)"
        AutoPositionWindow/M=1/R=$(WinName(0,1)) $WinName(0,2)
End     // end macro PlotSmearedPower_Law

Function Power_Law_model(w,x) : FitFunc
        Wave w
        Variable x
//       Input (fitting) variables are:
        //[0] Coefficient
        //[1] (-) Power
        //[2] incoherent background
//      give them nice names
        Variable A, m,bgd
        A = w[0]
        m = w[1]
        bgd = w[2]
        
//      local variables
        Variable inten, qval
//      x is the q-value for the calculation
        qval = x
//      do the calculation and return the function value
        
        inten = A*qval^-m + bgd
        Return (inten)
End
/////////////////////////////////////////////////////////////////////////////////


// this is all there is to the smeared calculation!
Function SmearedPower_Law_Model(w,x) :FitFunc
        Wave w
        Variable x
        
        Variable ans
        SVAR sq = gSig_Q
        SVAR qb = gQ_bar
        SVAR sh = gShadow
        SVAR gQ = gQVals
        
        //the name of your unsmeared model is the first argument
        ans = Smear_Model_20(Power_Law_model,$sq,$qb,$sh,$gQ,w,x)

        return(ans)
End