Fortran-callable routine to decode text strings containing integers.
The text string may be padded with any number of blanks between
the integers, but there may be no imbedded blanks in the integers
themselves.   Any character other than a digit, sign or blank will
be interpreted as a separator for an omitted number.

Calling sequence --  call DECODI(text,pos,end,num1)
TEXT    Array of text input to DECODI.
POS     Starting character position in string for decoding.
END     Last character position in string for decoding.
NUM1    Integer to be read from string.
NOTE: If the text string runs out before NUM1 is filled, NUM1 will
be zeroed.  Originally, multiple integers could be specified, but
the Fortran version can handle only one.

On return from DECODI, 'POS' will contain the position of the next
character remaining undecoded.  Any non-numeric character other than
a sign used to terminate a number will be considered "decoded" when
encountered.
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