| T O P I C R E V I E W |
| mwmarmw |
Posted - 07/05/2021 : 07:13:09 AM
Hello, I am doing NLCF. My question is how do I set up parameter initialization for a function of the following form:
y=k*(x^c)+l*(x^d)+a*(1-exp(-b*x))
I tried something like that:
sort( x_y_curve );
//smooth( x_y_curve, 2 );
Dataset dx;
x_y_curve.AttachX(dx);
dx = ln(dx);
x_y_curve = ln( x_y_curve );
Dataset coeff;
coeff.SetSize(2);
fitpoly( x_y_curve, 1, coeff);
k= exp( coeff[0] );
c = coeff[1];
coeff.SetSize(3);
fitpoly( x_y_curve, 1, coeff);
l = exp( coeff[0] );
d = coeff[1];
int sign;
double a1;
b = -get_exponent_cuv(x_y_curve, &a1, &a, &sign);
a = (a1-sign*exp(a)) / 2;
but there is definitely some error in it (maybe in a different place of the function being built?), Because although the curve fits well, the parameters obtained have undefined values.
I will appreciate any help |
| 1 L A T E S T R E P L I E S (Newest First) |
| Chris D |
Posted - 07/06/2021 : 12:11:14 PM
Hi,
Can you submit a support ticket about this and please provide a dataset for use to test with.
https://www.originlab.com/restricted/support/index.aspx?c=3
Thanks,
Chris Drozdowski
Originlab Technical Support
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