SLA_DCMPF - Interpret Linear Fit

From d54fe7c1f704a63824c5bfa0ece65245572e9b27 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 4 Mar 2015 21:21:30 -0500 Subject: Initial commit --- src/slalib/sun67.htx/node50.html | 166 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 src/slalib/sun67.htx/node50.html (limited to 'src/slalib/sun67.htx/node50.html') diff --git a/src/slalib/sun67.htx/node50.html b/src/slalib/sun67.htx/node50.html new file mode 100644 index 0000000..555de30 --- /dev/null +++ b/src/slalib/sun67.htx/node50.html @@ -0,0 +1,166 @@ + + + + +SLA_DCMPF - Interpret Linear Fit + + + + + + + + + + + + +

+ +

+
+ Next: SLA_DCS2C - Spherical to Cartesian +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_DCC2S - Cartesian to Spherical +

SLA_DCMPF - Interpret Linear Fit + +

ACTION: +: Decompose an $[\,x,y\,]$ linear fit into its constituent parameters: +zero points, scales, nonperpendicularity and orientation. +
CALL: +: CALL sla_DCMPF (COEFFS,XZ,YZ,XS,YS,PERP,ORIENT) +

GIVEN: +

+
+ + + + + +

COEFFS	D(6)	transformation coefficients (see note)

RETURNED: +

+
+ + + + + + + + + + + + + + + + + + + + + + + + + +

XZ	D	x zero point
YZ	D	y zero point
XS	D	x scale
YS	D	y scale
PERP	D	nonperpendicularity (radians)
ORIENT	D	orientation (radians)

NOTES: +

1. +

The model relates two sets of $[\,x,y\,]$ coordinates as follows. +Naming the six elements of COEFFS a,b,c,d,e & f, +the model transforms coordinates $[x_{1},y_{1}\,]$ into coordinates + $[x_{2},y_{2}\,]$ as follows: +

x₂ = a + bx₁ + cy₁
+ y₂ = d + ex₁ + fy₁

+ The sla_DCMPF routine decomposes this transformation + into four steps: +

(a) +: Zero points: +
$x' = x_{1} + {\rm XZ}$
+ $y' = y_{1} + {\rm YZ}$
+
(b) +: Scales: +
$x'' = x' {\rm XS}$
+ $y'' = y' {\rm YS}$
+
(c) +: Nonperpendicularity: +
$x''' = + x'' \cos {\rm PERP}/2 + y'' \sin {\rm PERP}/2$
+ $y''' = + x'' \sin {\rm PERP}/2 + y'' \cos {\rm PERP}/2$
+
(d) +: Orientation: +
$x_{2} = + x''' \cos {\rm ORIENT} + + y''' \sin {\rm ORIENT}$
+ $y_{2} = - x''' \sin {\rm ORIENT} + + y''' \cos {\rm ORIENT}$

2. +

See also sla_FITXY, sla_PXY, sla_INVF, sla_XY2XY. +

+ +

+
+ Next: SLA_DCS2C - Spherical to Cartesian +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_DCC2S - Cartesian to Spherical +

+SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk +

+ + -- cgit