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f( x ) = a * x^b + c Regression for the basic exponentiation function.

Note that this function can also be used for inverse functions in the form f( x ) = a / x^b + c be having a negative value for b.

package GaussNewtonRegression
subpackage ExponentiationRegression

 Methods

Evaluate function at x.

getFunction(float $x, array $coefficients) : float

Return f( x ) for a given set of coefficients.

Parameters

$x

float

Real value given to equation.

$coefficients

array

Coefficients used in calculation.

Returns

floatValue result of equation.

Number of coefficients.

getNumberOfCoefficients() : integer

Returns

integerThe number of coefficients for the equation being used.

Partial differential.

partialDifferential(float $x, integer $coefficientIndex, array $coefficients) : float

Parameters

$x

float

Value of x to supply to partial-differential function.

$coefficientIndex

integer

Which coefficient to be used in the partial-differential function.

$coefficients

array

Values of the coefficients to be used.

Returns

floatp( x ) for the supplied input.