1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
program intrinsics_213
! Which is faster: exp or log?
integer:: n, k = 2
real:: x,dx,y,z,t1,t2
print "(A,I0)",'k = ',k
dx = 1e-6
call cpu_time(t1)
x = 0
do n = 1,10**k
x = x+dx
z = exp(-1/x)
end do
call cpu_time(t2)
print "(2(A,F10.3))",'after 10**k exp, abs(t2-t1) = ',abs(t2-t1),' s; z=',z
if (abs(z) > 1e-8) error stop
x = 1
do n = 1,10**k
x = x+dx
z = log(x)
end do
call cpu_time(t1)
print "(2(A,F10.3))",'after 10**k log, abs(t2-t1) = ',abs(t2-t1),' s; z=',z
if (abs(z - (9.53628842e-05)) > 1e-8) error stop
end program intrinsics_213
|
