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Define Data Scaling Parameters and Undefined Pixel Flags

These subroutines define or modify the internal parameters used by FITSIO to either scale the data or to represent undefined pixels. These subroutines do not create or modify the corresponding header keyword values, if any, and it is the user's responsibility to ensure that the two are consistent.

1

Reset the scaling factors in the primary array or image extension; does not change the BSCALE and BZERO keyword values and only affects the automatic scaling performed when the data elements are written/read to/from the FITS file. When writing to a new FITS file, this subroutine must be called after the call to ftpdef. (NOTE: BSCALE and BZERO must be declared as Double Precision variables).

FTPSCL(unit,bscale,bzero, > status)

2

Reset the scaling parameters for a table column; does not change the TSCALnnn or TZEROnnn keyword values and only affects the automatic scaling performed when the data elements are written/read to/from the FITS file. When writing to a new FITS extension, this subroutine must be called after the call to ftadef or ftbdef. (NOTE: TSCAL and TZERO must be declared as Double Precision variables).

FTTSCL(unit,colnum,tscal,tzero, > status)

3

Define the integer value to be used to signify undefined pixels in the primary array or image extension. This is only used if BITPIX = 8, 16, or 32. This does not create or change the value of the BLANK keyword in the header. When writing to a new FITS file, this subroutine must be called after the call to ftpdef.

FTPNUL(unit,blank, > status)

4

Define the string to be used to signify undefined pixels in a column in an ASCII table. This does not create or change the value of the TNULLn keyword. When writing to a new FITS file, this subroutine must be called after the call to ftadef.

FTSNUL(unit,colnum,snull > status)

5

Define the value to be used to signify undefined pixels in an integer column in a binary table. This does not create or change the value of the TNULLn keyword. When writing to a new FITS file, this subroutine must be called after the call to ftbdef.

FTTNUL(unit,colnum,tnull > status)