Previous: FITS ASCII and Binary Table Data I/O Subroutines
Up: Subroutine Calling Sequence Definitions
Previous Page: High-Level Table Access Subroutines
Next Page: Summary of all FITSIO User-Interface Subroutines

General Utility Subroutines

The following utility subroutines may be useful for certain applications:

1

Return the revision number of the fitsio library. This subroutine returns the current revision number of the FITSIO software library. The revision number will be incremented whenever any modifications or enhancements are made to the code.

FTVERS( > version)

2

Return the descriptive text string corresponding to a FITSIO error status code. The 30-character length string contains a brief description of the cause of the error.

FTGERR(status, > errtext)

3

Convert a character string to uppercase (operates in place).

FTUPCH(string)

4

Test that the keyword name contains only legal characters: A-Z,0-9, hyphen, and underscore.

FTTKEY(keyword,status)

5

Parse a header keyword record. This subroutine parses the input header record to return the value (as a character string) and comment strings. If the keyword has no value (columns 9-10 not equal to '= '), then the value string is returned blank and the comment string is set equal to column 9 - 80 of the input string.

FTPSVC(card, > value,comment,status)

6

Construct a sequence keyword name (ROOT + nnn). This subroutine appends the sequence number to the root string to create a keyword name (e.g., 'NAXIS' + 2 = 'NAXIS2')

FTKEYN(keyroot,seq_no, > keyword,status)

7

Determine the datatype of a keyword value string. This subroutine parses the keyword value string (usually columns 11-30 of the header record) to determine its datatype.

FTDTYP(value, > dtype,status)

8

Parse the 'TFORM' binary table column format string. This subroutine parses the input TFORM character string and returns the integer datatype code, the repeat count of the field, and, in the case of character string fields, the length of the unit string. The following datatype codes are used:

Datatype                DATTYP value
                bit, X                  11 (interpreted as a byte array, B)
                byte, B                 11
                logical, L              14
                ASCII character, A      16
                short integer, I        21
                integer, J              41
                real, E                 42
                double precision, D     82
                complex                 83
                double complex          163

        FTBNFM(tform, > dattyp,repeat,width,status)

9

Calculate the starting column position and total ASCII table width based on the input array of ASCII table TFORM values. The SPACE input parameter defines how many blank spaces to leave between each column (it is recommended to have one space between columns for better human readability).

FTGABC(tfields,tform,space, > rowlen,tbcol,status)

10

Parse a template string and return a formatted 80-character string suitable for appending to (or deleting from) a FITS header file. This subroutine is useful for parsing lines from an ASCII template file and reformatting them into legal FITS header records. The formatted string may then be passed to the FTPREC, FTMCRD, or FTDKEY subroutines to append or modify a FITS header record.

FTGTHD(template, > card,hdtype,status)

-

The KEYNAME token must begin in columns 1-8 and be a maximum of 8 characters long. If the first 8 characters of the template line are blank then the remainder of the line is considered to be a FITS comment (with a blank keyword name). A legal FITS keyword name may only contain the characters A-Z, 0-9, and '-' (minus sign) and underscore. This subroutine will automatically convert any lowercase characters to uppercase in the output string. If KEYNAME = 'COMMENT' or 'HISTORY' then the remainder of the line is considered to be a FITS COMMENT or HISTORY record, respectively.

-

The VALUE token must be separated from the KEYNAME token by one or more spaces and/or an '=' character. The datatype of the VALUE token (numeric, logical, or character string) is automatically determined and the output CARD string is formatted accordingly. The value token may be forced to be interpreted as a string (e.g. if it is a string of numeric digits) by enclosing it in single quotes.

-

The COMMENT token is optional, but if present must be separated from the VALUE token by at least one blank space. A leading '/' character may be used to mark the beginning of the comment field, otherwise the comment field begins with the first non-blank character following the value token.

-

One exception to the above rules is that if the first non-blank character in the template string is a minus sign ('-') followed by a single token, or a single token followed by an equal sign, then it is interpreted as the name of a keyword which is to be deleted from the FITS header.

-

The second exception is that if the template string starts with a minus sign and is followed by 2 tokens then the second token is interpreted as the new name for the keyword specified by first token. In this case the old keyword name (first token) is returned in characters 1-8 of the returned CARD string, and the new keyword name (the second token) is returned in characters 41-48 of the returned CARD string. These old and new names may then be passed to the FTMNAM subroutine which will change the keyword name.

The HDTYPE output parameter indicates how the returned CARD string should be interpreted:

hdtype                  interpretation
        ------           -------------------------------------------------
           -2            Modify the name of the keyword given in CARD(1:8)
                         to the new name given in CARD(41:48)

           -1            CARD(1:8) contains the name of a keyword to be deleted
                         from the FITS header.

            0            append the CARD string to the FITS header if the
                         keyword does not already exist, otherwise update
                         the value/comment if the keyword is already present
                         in the header.

            1            simply append this keyword to the FITS header (CARD
                         is either a HISTORY or COMMENT keyword).

            2            This is a FITS END record; it should not be written
                         to the FITS header because FITSIO automatically
                         appends the END record when the header is closed.

INTVAL 7 This is an integer keyword
      RVAL           34.6   /     This is a floating point keyword
      EVAL=-12.45E-03  This is a floating point keyword in exponential notation
      lval F This is a boolean keyword
                  This is a comment keyword with a blank keyword name
      SVAL1 = 'Hello world'   /  this is a string keyword
      SVAL2  '123.5'  this is also a string keyword
      sval3  123+  /  this is also a string keyword with the value '123+    '
      # the following template line deletes the DATE keyword
      - DATE
      # the following template line modifies the NAME keyword to OBJECT
      - NAME OBJECT