NLFitSession::Fit

Description

Perform the fit. Iterations will be carried out until the tolerance is reached, or the number of iterations has reached the maximum specified by SetMaxNumIter.

Syntax

bool Fit(int* pnOutcome = NULL, bool bCheckLastOutcome = false, bool bAllowCancel = false)

Parameters

pnOutcome
[output] the int pointer, if not NULL, receive the error code.
bCheckLastOutcome
[input] if ture, will not iteration again if already converged.
bAllowCancel
[input] if true to allow type Esc to interrupt iteration.

Return

return ture if fit converged, else return false.

Examples

EX1

  1. Prior to running the following example, the nlsf_utils.c file need to be loaded and compiled. This can be done from script with the command run.LoadOC(Originlab\nlsf_utils.c) or just add this file to your workspace.
  2. New a worksheet and import \Samples\Curve Fitting\Gaussian.dat.
  3. Copy and compile the following codes, and run "NLFitSession_Fit_ex1" in Command window.

#include <..\originlab\NLFitSession.h>
void NLFitSession_Fit_ex1()
{
    Worksheet   wks = Project.ActiveLayer();
    if( !wks )
        return;
    
    wks.SetSize(-1, 2); // remove other columns
    wks.SetSize(-1, 4); // add two new columns
    wks.SetColDesignations("XYXY");
    
    XYRange     dr;
    // add input data range
    dr.Add(wks, 0, "X");
    dr.Add(wks, 1, "Y");
    dr.Add();
    // add output fit data range
    dr.Add(wks, 2, "X");
    dr.Add(wks, 3, "Y");
    
    int    nRangeIndex = 0;
    vector      vX, vY;
    dr.GetData(vY, vX, NULL, nRangeIndex); 
  

    NLFitSession    FitSession;
    
    // 1. set function
    if( !FitSession.SetFunction("Gauss")) // set function as Gauss, category name can be ignore
    {
        out_str("invalid fit function");
        return;
    }   
    
    // 2. set data
    if( !FitSession.SetData(vY, vX))
    {
        out_str("fail to set data");
        return;
    }
    
    // 3. init parameter
    if( !FitSession.ParamsInitValues())
    {
        out_str("fail to init parameter");
        return;
    }
    
    out_str("The parameter values before fitting");
    FitSession.GetChiSqr(); // call GetChiSqr order to set parameter settings on internal fit object
    show_params(FitSession);
    
    // 4. fit
    int nOutcome;
    if( !FitSession.Fit(&nOutcome) )
    {
        out_str("Fail to do fitting");
        return;
    }
 
    out_str("The parameter values after fitting");
    show_params(FitSession);
    
    
    // 5. get fitting xy data and put to source worksheet
    double         xmin, xmax, xinc;
    vX.GetMinMax(xmin, xmax);
    
    int    count = 100;
    RoundLimits(&xmin, &xmax, &xinc, count);
    
    vector      vFitX, vFitY;
    vFitX.Data(xmin, xmax, xinc);
    vFitY.SetSize(vFitX.GetSize());
    
    if( 0 == FitSession.GetYFromX(vFitX, vFitY, vFitX.GetSize()) )
    {
        out_str("Fail to get Y values");
    }
    
    nRangeIndex = 1;
    dr.SetData(&vFitY, &vFitX, nRangeIndex); 
    
    // plot source data and fitting data
    GraphPage gp;
    gp.Create();
    GraphLayer gl = gp.Layers();
    if( gl.AddPlot(wks) >= 0 )
        legend_update(gl);
}
 
void show_params(NLFitSession& FitSession)
{
    // get parameter values after initialization
    vector      vParamValues;
    vector<int> vnParamsOffsets; // the begin index of one group of parameters, normally one group for one dataset
    FitSession.GetParamValuesAndOffsets(vParamValues, vnParamsOffsets);
    
    // output parameter values with names
    vector<string> vsParamNames;
    FitSession.GetParamNamesInFunction(vsParamNames);   
        
    int nDataset = 0;
    for( int nParam = vnParamsOffsets[nDataset], ii = 0; nParam < vnParamsOffsets[nDataset+1]; nParam++, ii++ )
    {
        printf("%s = %f\n", vsParamNames[ii], vParamValues[nParam]);
    }   
}

Remark

See Also

GetFitOutCome

Header to Include

Originlab\NLFitSession.h