>  Docs Center  >  Libraries  >  ASTROLIB  >  SIP_EVAL

SIP_EVAL

SIP_EVAL

Name


    SIP_EVAL

Purpose


    Compute distorted coordinates given SIP (simple imaging polynomial)
    coefficients.

Explanation


    See http://fits.gsfc.nasa.gov/registry/sip.html for the SIP convention
     
    The coefficients are passed via common block. This is because this
    routine is called by the intrinisc BROYDEN() function in AD2XY, and
    common blocks are the only way to pass parameters to the user supplied
    function in BROYDEN().

Calling Sequence


    res = SIP_EVAL(xy)

Inputs


    xy - 2 elements vector giving the undistorted X,Y position

Outputs


    res - 2 element vector giving the distorted position

Common Blocks


      common broyden_coeff,xcoeff,ycoeff
      XCOEFF, YCOEFF are both nxn arrays giving the SIP coefficient for an
      n x n polynomial.

Revision History


    Written W. Landsman Dec 2013



© 2019 Harris Geospatial Solutions, Inc. |  Legal
My Account    |    Store    |    Contact Us