accuracy=2.0d-8

[nnnnn]

Dear friends;
What dose "d-8" mean in Fortran?
Thanks

[jtbell]

2.0d-8 is the same value as 2.0e-8 except that it's stored as a double precision real number instead of single precision. In FORTRAN 77 it would be declared as REAL*16 instead of REAL*8.

[nnnnn]

Much thanks to jtbell ;

you mean 2.0d-8 is equal to 2*10^ (-8) ?

[jtbell]

Yes.