Regress.TRegressFun Type

Defines regression function.

Pascal

TRegressFun = function (const B: TVec; X: double): double;

File

Regress

Description

The type describes the regression function of several regression parameters (B array) and independent variable X. The TRegressFun is used in several regression procedure. For higher (vectorized) performance see TMultiRegressFun.

See Also

TDeriveProc

Example 1

Some examples of regression function: Polynomial of 2nd degree (parabola)

// y=b0*x*x + b1*x + b2
function SimpleParabola(const B: TVec; X: double): double;
begin
  SimpleParabola := b[0]*Sqr(x) + b[1]*x + b[2];
end;

double __fastcall SimpleParabola(TVec * const b, double x)
{
  double* B = b->PValues1D(0);
  return B[0]*x*x + B[1]*x + B[2];
}

Examples on GitHub

Example 2

"Eckerle4" function from NIST files:

function Eckerle4(const B: TVec; X: double): double;
begin
  Eckerle4 := B[0]/B[1] * Exp(-0.5*Sqr((X-B[2])/B[1]));
end;

double __fastcall Eckerle4(TVec* const b, double x)
{
  double* B = b->PValues1D(0);

  double sqrterm = (x-B[2])/B[1])*(x-B[2])/B[1]);
  return B[0]/B[1] * Exp(-0.5*(sqrterm));
}

Regress, Types, Example 1, Example 2, See Also

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