double precision function dmach(job) integer job c c smach computes machine parameters of floating point c arithmetic for use in testing only. not required by c linpack proper. c c if trouble with automatic computation of these quantities, c they can be set by direct assignment statements. c assume the computer has c c b = base of arithmetic c t = number of base b digits c l = smallest possible exponent c u = largest possible exponent c c then c c eps = b**(1-t) c tiny = 100.0*b**(-l+t) c huge = 0.01*b**(u-t) c c dmach same as smach except t, l, u apply to c double precision. c c cmach same as smach except if complex division c is done by c c 1/(x+i*y) = (x-i*y)/(x**2+y**2) c c then c c tiny = sqrt(tiny) c huge = sqrt(huge) c c c job is 1, 2 or 3 for epsilon, tiny and huge, respectively. c double precision eps,tiny,huge,s c eps = 1.0d0 10 eps = eps/2.0d0 s = 1.0d0 + eps if (s .gt. 1.0d0) go to 10 eps = 2.0d0*eps c s = 1.0d0 20 tiny = s s = s/16.0d0 if (s*1.0 .ne. 0.0d0) go to 20 tiny = (tiny/eps)*100.0 huge = 1.0d0/tiny c if (job .eq. 1) dmach = eps if (job .eq. 2) dmach = tiny if (job .eq. 3) dmach = huge return end