Previous: utrp10 Up: ../plot79_u.html Next: utrpp3

UTRP2

       INTEGER FUNCTION  UTRP2(X)
 C$    (Power-of-Two)
 C$    This  function  performs  the  seemingly  trivial  task  of
 C$    determining the power of  two for the  argument X when  the
 C$    mantissa lies  in  the  range (1,2-DELTA)  (DELTA  a  small
 C$    number).
 C$
 C$    The  first  step  required  is  to  determine  the  machine
 C$    precision, that is,  to find  the smallest  value EPS  such
 C$    that 1.0 +  EPS is  different from  1.0.  This  is done  by
 C$    FUNCTION UTREPS, rather than by setting the value in a DATA
 C$    statement in order  to make the  code machine  independent.
 C$    Experiments indicate that  the internal form  of a  decimal
 C$    number may be incorrect by as much as 2*EPS, so to be safe,
 C$    the quantity 10*EPS is used as a tolerance.
 C$    (09-APR-82)