3 and 9 level Vanvleck Corrections

Fred Schwab of NRAO wrote an excellent paper on the subject of 3 and 9 level vanvleck corrections entitled: DRAFT, Van Vleck Correction for the GBT correlator, Feb 11, 2002. Fred works in Fortran and we work in C. Here are Fred's routines converted to C and our interface. These include:

• vanvleck3lev( double *, npts ) - corrects a double array of acfs
• vanvleck9lev( double *, npts ) - corrects a double array of acfs
• vanvleck3levf( float *, npts ) - corrects a float array of acfs
• vanvleck9levf( float *, npts ) - corrects a float array of acfs
• double pow3lev(zho); - compute 3 level power based on zero lag (1 optimium)
• double pow9lev(zho); - compute 9 level power based on zero lag (1 optimium)
• double attndb3lev(zho); - compute db correction to optimium power
• double attndb9lev(zho); - compute db correction to optimium power

• Fred Schwab's Document
• Fred Schwab's Code converted to C
• Fred Schwab's inverse_cerf function converted to C

Thanks to Bill Sisk (bsisk@naic.edu) who researched this out, got it working first, and taught me how it works.