GENPOLY Command Reference Page

Module SENSORM :: GENPOLY

Generic polynomial conversion function.

Syntax

GENPOLY( VIN, [NORDER,] VCOEFFS, VOUT )

Parameters

VIN: Input data values; FLOAT PIPE
NORDER: Order of the polynomial function; WORD CONSTANT
VCOEFFS: Coefficients of the polynomial; FLOAT VECTOR
VOUT: Output data values; FLOAT PIPE

Description

The GENPOLY command is a general purpose mapping from a stream of input data received from pipe VIN, to produce a stream of output data in pipe VOUT. One common application of this command is mapping measurements of an arbitrary nonlinear sensor into the equivalent measurement in the desired physical units.

The polynomial mapping is determined by the VCOEFFS vector. The coefficients specified in this vector start with the zero-order term, followed by the first-order term, followed by the second-order term, etc. up to the order specified by the NORDER parameter. If you omit the NORDER parameter, the command will count terms and assume the corresponding maximum order.

Using only a first-order polynomial, this command becomes equivalent to a SCALE command. From the opposite point of view, this command covers the functionality of the SCALE command at the same time that it performs nonlinear mappings. When using this command for "linearizing" the response of a nonlinear sensor, it can at the same time provide gain and offset corrections.

Examples

 
    VECTOR   VCOEFFS FLOAT  =  ( 1.0, 3.085e-3, -5.707e-7 )
    CONSTANT ORDER   WORD   =  2
    ...
    GENPOLY( PIN, ORDER, VCOEFFS, POUT )

Take values X from the PIN pipe one at a time, and for each one apply the second-order polynomial mapping

   Y  = 1.0 + 3.085e-3*X + -5.707e-7*X²

to obtain the values Y that are placed into the output data stream POUT.

DAPL Operating System | Processing Command