NAME
        dbf - convert FFP dual-binary number to FFP format

   SYNOPSIS
        fnum = dbf(exp, mant);

   FUNCTION
        Accepts a dual-binary format (described below) floating point
        number and converts it to an FFP format floating point number.
        The dual-binary format is defined as:

                exp bit  16     = sign (0=>positive, 1=>negative)
                exp bits 15-0   = binary integer representing the base
                                          ten (10) exponent
                man             = binary integer mantissa

   INPUTS
        exp - binary integer representing sign and exponent
        mant - binary integer representing the mantissa

   RESULT
        fnum - converted FFP floating point format number

   BUGS
        None