question on precision

[coolweather]

my variables are declared as

integer, parameter :: varsize = 8

real(varsize), allocatable :: myarray (:,:,:)

and I need to compute using some trigonometric functions with as maximum precision as possible

shoud I use dcos, dsin, dacos,... functions insteed of sin, cos.... ?

what will be the difference in precision (significant numbers after point) in the both cases ?

thank you !

[TimP]

The generic intrinsics (since 30 years ago) such as sin, cos automatically adjust to the kind of the argument, so
sin(myarray)
will give you the identical library function as the style prior to 30 years ago
dsin(myarray)
except that the latter probably breaks when varsize changes. The specific kind number 8 of course works for Intel compilers but not all other brands. This gives you about 16 significant decimal precision (see spacing(x), since 20 years ago), counting before and after decimal point.
ifort, and several other compilers, also have quad precision math libraries which come in for varsize=selected_real_kind(30), at a cost in performance.