bool ASP_VO2_fit_PWL3(vector vX, vector vY, vector& vParam, double dXval, int fix)
{
	NLFitSession nlfS;
	nlfS.SetFunction("PWL3");
	nlfS.SetData(vY, vX);
	
	// Initialisation
	vector vParamValues(6);
    vector<int> vnParamsOffsets(6); // the begin index of one group of parameters, normally one group for one dataset
    
	nlfS.ParamsInitValues();
	nlfS.GetParamValuesAndOffsets(vParamValues, vnParamsOffsets);
	
	if (fix > 0) // if fix xi1 or xi2
	{
		if (fix == 1) // fix xi1
		{
			vParamValues[2] = dXval;
			nlfS.SetParamFix(2, true);
		}
		if (fix == 2) // fix xi2
		{
			vParamValues[4] = dXval;
			nlfS.SetParamFix(4, true);
		}
		nlfS.SetParamValues(vParamValues);
	}
    
    // Fit
    vector vErr(6);
    
	if (nlfS.Fit())
	{
		nlfS.GetFitResultsParams(vParam, vErr);
		return true;
	}
	
	return false;
}

quote:

---

Originally posted by couturier

Origin Ver. and Service Release (Select Help-->About Origin): 2020b
Operating System:win10 64bit

Hi,

I have some troubles fixing parameters with PWL3 fit function.
Here's my code:

bool ASP_VO2_fit_PWL3(vector vX, vector vY, vector& vParam, double dXval, int fix)
{
	NLFitSession nlfS;
	nlfS.SetFunction("PWL3");
	nlfS.SetData(vY, vX);
	
	// Initialisation
	vector vParamValues(6);
    vector<int> vnParamsOffsets(6); // the begin index of one group of parameters, normally one group for one dataset
    
	nlfS.ParamsInitValues();
	nlfS.GetParamValuesAndOffsets(vParamValues, vnParamsOffsets);
	
	if (fix > 0) // if fix xi1 or xi2
	{
		if (fix == 1) // fix xi1
		{
			vParamValues[2] = dXval;
			nlfS.SetParamFix(2, true);
		}
		if (fix == 2) // fix xi2
		{
			vParamValues[4] = dXval;
			nlfS.SetParamFix(4, true);
		}
		nlfS.SetParamValues(vParamValues);
	}
    
    // Fit
    vector vErr(6);
    
	if (nlfS.Fit())
	{
		nlfS.GetFitResultsParams(vParam, vErr);
		return true;
	}
	
	return false;
}

if fix = 0, fitting should be free
if fix = 1, I want to fix xi1 (3rd parameter) as dXval
if fix = 2, I want to fix xi2 (4th parameter) as dXval

When fix > 0, I get different result than fix = 0, but xi1 or xi2 are not fixed to dXval

What am I doing wrong ?

Bonus question:
I tried NLFit Class and got results 10 times faster.
But I couldn't find how to fix parameters.
Is it possible ?

---

if(fix == 1)
{
    vParamValues[2] = dXval;
    nlfS.SetParamValues(vParamValues);
    nlfS.SetParamFix(2, true);
}

int NLFit::SetParams(int nNumParamValues, double *pdParamValues, int *pbShared = NULL, bool *pbFixed = NULL, bool bLoadBoundsFromFunctions = true);

int nNumParamValues = vParamValues.GetSize();
vector<bool> vbFixed(nNumParamValues);
vbFixed = false;
if(fix == 1)
{
    vParamValues[2] = dXval;
    vbFixed[2] = true;
}
fit.SetParams(nNumParamValues, &vParamValues[0], NULL, &vbFixed[0], true);

                                          &&&&&&&&&
                                        &&&
                                       &&
                                      &  _____ ___________
                                     II__|[] | |   I I   |
                                    |        |_|_  I I  _|
                                   < OO----OOO   OO---OO
**********************************************************

int nErr;
fn.ParamInit( vParams, vX, vY, nErr );

quote:

---

Originally posted by couturier

Thanx a lot Castiel, it works great now

I switched to NLFit and it is MUCH faster than NLFitSession

That brings another question:
I have another function for fitting 2 datasets, with some fixed parameters and parameters sharing.

I have no idea on how to use ParamInit() for such a case.
Only examples I could find where like

int nErr;
fn.ParamInit( vParams, vX, vY, nErr );

For now, I'm using my previous function ASP_VO2_fit_PWL3() on each dataset to get initial values, but I guess I could use ParamInit() ?

thanx

---

BOOL NumericFunction::ParamInit(vector& vParams, vector& vIndependent, vector& vDependent, int& nErr = NULL, ParamInitContext& ctxt = NULL);

BOOL NLFit::SetParametersBounds(BOOL bUpper, double *pdBoundsValues, bool *pbExclusive, int nNumBounds);

                                          &&&&&&&&&
                                        &&&
                                       &&
                                      &  _____ ___________
                                     II__|[] | |   I I   |
                                    |        |_|_  I I  _|
                                   < OO----OOO   OO---OO
**********************************************************

quote:

---

There are many examples in <exe>\OriginC\system\ONLSF.h you could follow (unless there are mutiple indeps/deps.)

---

quote:

---

you could use that method:
BOOL NumericFunction::ParamInit(vector& vParams, vector& vIndependent, vector& vDependent, int& nErr = NULL, ParamInitContext& ctxt = NULL);

---

quote:

---

To set constraints, call

BOOL NLFit::SetParametersBounds(BOOL bUpper, double *pdBoundsValues, bool *pbExclusive, int nNumBounds);

---

quote:

---

Originally posted by couturier

quote:

---

There are many examples in <exe>\OriginC\system\ONLSF.h you could follow (unless there are mutiple indeps/deps.)

---

Yes, I had seen them

quote:

---

you could use that method:
BOOL NumericFunction::ParamInit(vector& vParams, vector& vIndependent, vector& vDependent, int& nErr = NULL, ParamInitContext& ctxt = NULL);

---

The thing is I have 2 dependent vectors.
Didn't see any example about that

quote:

---

To set constraints, call

BOOL NLFit::SetParametersBounds(BOOL bUpper, double *pdBoundsValues, bool *pbExclusive, int nNumBounds);

---

\OriginC\system\ONLSF.h is quite cryptic to me
How pdBoundsValues are arranged ? all lowers and the all uppers, uppers - lowers ?

In the function initially posted, how could I set xi1 to be greater than Xmin+value1, and lower than Xmax-value2, and xi2 to be greater than Xmin+value3, and lower than Xmax-value3 ?

---

BOOL NumericFunction::ParamInit(vector& vParams, vector *pvIndeps, vector *pvDeps, int& nErr = NULL, ParamInitContext& ctxt = NULL);

int NLFit::SetData(int nNumberDatasetSets, NLSFONEDATA *pstDependentData, NLSFONEDATA *pstdIndependentData, ONEDATAWEIGHT *pWeightDep = NULL, ONEDATAWEIGHT* pWeightIndep = NULL);

/*
vector x1, x2;  // independents
vector y1, y2;  // dependents
*/

vector vIndeps[2];
vIndeps[0] = x1;
vIndeps[1] = x2;

vector vDeps[2];
vDeps[0] = y1;
vDeps[1] = y2;

vector vParams;
BOOL bRet = nf.ParamInit(vParams, &vIndeps[0], &vDeps[0], NULL, NULL);

/*
NLFit fit;
*/

NLSFONEDATA stIndependentData[2], stDependentData[2];
stIndependentData[0].pdData = &x1[0];
stIndependentData[0].nSize = x1.GetSize();
stIndependentData[1].pdData = &x2[0];
stIndependentData[1].nSize = x2.GetSize();
stDependentData[0].pdData = &y1[0];
stDependentData[0].nSize = y1.GetSize();
stDependentData[1].pdData = &y2[0];
stDependentData[1].nSize = y2.GetSize();

int nDatasets = 1;
int nRet = fit.SetData(nDatasets, &stDependentData[0], &stIndependentData[0], NULL, NULL);

BOOL NLFit::SetParametersBounds(BOOL bUpper, double *pdBoundsValues, bool *pbExclusive, int nNumBounds);

                                          &&&&&&&&&
                                        &&&
                                       &&
                                      &  _____ ___________
                                     II__|[] | |   I I   |
                                    |        |_|_  I I  _|
                                   < OO----OOO   OO---OO
**********************************************************