stellinstall/dpmpar_8f_source.html

      FUNCTION dpmpar (i)

      USE stel_kinds

      IMPLICIT NONE

C-----------------------------------------------

C   D u m m y   A r g u m e n t s

C-----------------------------------------------

      INTEGER :: i

      REAL(rprec) :: dpmpar

C-----------------------------------------------

c

c     FUNCTION dpmpar

c

c     this FUNCTION provides single (double) precision machine parameters

c     when the appropriate set of data statements is activated (by

c     removing the c from column 1) and ALL other data statements are

c     rendered inactive. most of the PARAMETER values were obtained

c     from the corresponding bell laboratories port library FUNCTION.

c

c     the FUNCTION statement is

c

c       FUNCTION dpmpar(i)

c

c     WHERE

c

c       i is an integer input variable set to 1, 2, or 3 which

c         selects the desired machine parameter. if the machine has

c         t base b digits and its smallest and largest exponents are

c         emin and emax, respectively, then these parameters are

c

c         dpmpar(1) = b**(1 - t), the machine precision,

c

c         dpmpar(2) = b**(emin - 1), the smallest magnitude,

c

c         dpmpar(3) = b**emax*(1 - b**(-t)), the largest magnitude.

c

c     argonne national laboratory. minpack project. march 1980.

c     burton s. garbow, kenneth e. hillstrom, jorge j. more

c

c     SINGLE PRECISION

c     data rmach(1)/1.490116100E-8/

c     data rmach(2)/1.4693679000E-30/

c     data rmach(3)/1.701411800E+30/

c     DOUBLE PRECISION - IEEE

c     data dmach(1) /2.22044604926d-16/

c     data dmach(2) /2.22507385852d-308/

c     data dmach(3) /1.79769313485d+308/

c     modified for f90 (sph, august 1997)

c

      SELECT CASE(i)

      CASE(:1)

        dpmpar = epsilon(dpmpar)      !2.22044604926e-16_dp

      CASE(2)

        dpmpar = tiny(dpmpar)         !2.22507385852e-308_dp

      CASE(3:)

        dpmpar = huge(dpmpar)         !1.79769313485e+308_dp

      END SELECT


      END FUNCTION dpmpar