SLA_PXY - Apply Linear Model   

ACTION:

Given arrays of expected and measured $[\,x,y\,]$ coordinates, and a linear model relating them (as produced by sla_FITXY), compute the array of predicted coordinates and the RMS residuals.

CALL:

CALL sla_PXY (NP,XYE,XYM,COEFFS,XYP,XRMS,YRMS,RRMS)

GIVEN:

NP number of samples

$$[\,x,y\,]$$ XYE D(2,NP)

$$[\,x,y\,]$$ XYM D(2,NP)

COEFFS D(6) coefficients of model (see below)

RETURNED:

$$[\,x,y\,]$$ XYP

XRMS D RMS in X

YRMS D RMS in Y

RRMS D total RMS (vector sum of XRMS and YRMS)

NOTES:

1.

The model is supplied in the array COEFFS. Naming the six elements of COEFFS a,b,c,d,e & f, the model transforms measured coordinates $[x_{m},y_{m}\,]$ into predicted coordinates $[x_{p},y_{p}\,]$ as follows:

x_p = a + bx_m + cy_m
y_p = d + ex_m + fy_m

2.

The residuals are (x_p-x_e) and (y_p-y_e).

3.

If NP is less than or equal to zero, no coordinates are transformed, and the RMS residuals are all zero.

4.

See also sla_FITXY, sla_INVF, sla_XY2XY, sla_DCMPF