From fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 8 Jul 2015 20:46:52 -0400 Subject: Initial commit --- math/slalib/doc/pcd.hlp | 51 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 math/slalib/doc/pcd.hlp (limited to 'math/slalib/doc/pcd.hlp') diff --git a/math/slalib/doc/pcd.hlp b/math/slalib/doc/pcd.hlp new file mode 100644 index 00000000..dd6263a4 --- /dev/null +++ b/math/slalib/doc/pcd.hlp @@ -0,0 +1,51 @@ +.help pcd Jun99 "Slalib Package" +.nf + + SUBROUTINE slPCD (DISCO,X,Y) + + - - - - + P C D + - - - - + + Apply pincushion/barrel distortion to a tangent-plane [x,y]. + + Given: + DISCO d pincushion/barrel distortion coefficient + X,Y d tangent-plane coordinates + + Returned: + X,Y d distorted coordinates + + Notes: + + 1) The distortion is of the form RP = R*(1 + C*R**2), where R is + the radial distance from the tangent point, C is the DISCO + argument, and RP is the radial distance in the presence of + the distortion. + + 2) For pincushion distortion, C is +ve; for barrel distortion, + C is -ve. + + 3) For X,Y in units of one projection radius (in the case of + a photographic plate, the focal length), the following + DISCO values apply: + + Geometry DISCO + + astrograph 0.0 + Schmidt -0.3333 + AAT PF doublet +147.069 + AAT PF triplet +178.585 + AAT f/8 +21.20 + JKT f/8 +13.32 + + 4) There is a companion routine, slUPCD, which performs + an approximately inverse operation. + + P.T.Wallace Starlink 31 December 1992 + + Copyright (C) 1995 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp -- cgit