FC_Poly5NormalizedCoefficients

FC_Poly5NormalizedCoefficients - General Information

Overview

Type:	Function
Available as of:	V1.0.3.0
Versions:	Current version

Task

Calculates the coefficients of a standardized polynomial from the boundary conditions.

Description

This function fulfils the same task as the function FC_Poly5Coefficients. The only difference is that a transition to a standardized X space is made before calculating the polynomial coefficients. This is effected by the following transformation:

P(X) = P_norm( (X - i_lrX0) / (i_lrX1 - i_lrX0) )

P_norm is a polynomial with an X space standardized to the interval [0, 1], for which the following holds:

P(i_lrX0) = P_norm(0)

P(i_lrX1) = P_norm(1)

Compared to FC_Poly5Coefficients, this way of proceeding has the advantage of a reduced sensitivity in relation to rounding errors (in particular if i_lrX0 is very large). A disadvantage, however, is that, in addition to the polynomial coefficients, the values i_lrX0 and i_lrX1 must be stored. This is effected in the extended polynomial coefficient structure ST_Poly5NormalizedCoefficients.

Interface

Input	Data type	Description
i_lrX0	LREAl	Left marginal point of the X interval
i_lrY0	LREAl	Required function value of the polynomial at the point i_lrX0
i_lrM0	LREAl	Required slope of the polynomial at the point i_lrX0
i_lrK0	LREAl	Required curvature of the polynomial at the point i_lrX0
i_lrX1	LREAl	Right marginal point of the X interval
i_lrY1	LREAl	Required function value of the polynomial at the point i_lrX1
i_lrM1	LREAl	Required slope of the polynomial at the point i_lrX1
i_lrK1	LREAl	Required curvature of the polynomial at the point i_lrX1

Output	Data type	Description
q_etDiag	GD.ET_Diag	General library-independent statement on the diagnostic. A value not equal to ET_Diag.Ok corresponds to an diagnostic message.
q_etDiagExt	ET_DiagExt	POU-specific output on the diagnostic. q_etDiag = ET_Diag.Ok -> Status message q_etDiag <> ET_Diag.Ok -> Diagnostic message

Output

Data type

Description

q_etDiag

GD.ET_Diag

General library-independent statement on the diagnostic.

A value not equal to ET_Diag.Ok corresponds to an diagnostic message.

q_etDiagExt

ET_DiagExt

POU-specific output on the diagnostic.

q_etDiag = ET_Diag.Ok -> Status message

q_etDiag <> ET_Diag.Ok -> Diagnostic message

Return Value

Data type	Description
ST_Poly5NormalizedCoefficients	Structure of the coefficients as well as of the interval limits of the polynomial.

Diagnostic Messages

q_etDiag	q_etDiagExt	Enumeration value	Description
OK	Ok	0	Ok
InputParameterInvalid	DefinitionXInterval	97	The definition of the X interval is invalid.

DefinitionXInterval

Enumeration name:	DefinitionXInterval
Enumeration value:	97
Description:	The definition of the X interval is invalid.

Issue	Cause	Solution
-	The definition of the X interval via i_lrX1 and i_lrX0 is invalid.	The following must hold: i_lrX1> i_lrX0

Enumeration name:	Ok
Enumeration value:	0
Description:	Ok

The coefficients have been calculated successfully.