Compute Pi to an arbitrary number of digits using VAX FORTRAN
Compute pi to an arbitrary number of digits using VAX FORTRAN. Why, you ask? Why not?
The program uses Machin’s series for computation of pi. See https://en.wikipedia.org/wiki/John_Machin for details.
Set DIGITS in the source file PI.FOR to the number of digits desired.
To compile/link under VMS:
$ FORTRAN/LIS PI.FOR$ LINK PI
And to run it, just:
$ RUN PI
This is standard FORTRAN, however, so it should run with little problem on other platforms. It is F77, as I recall.
You may have some issues with standard integers if your compiler doesn’t have the equivalent of an “unsigned” integer. VAX FORTRAN doesen’t know of unsigned integers, so I store 4 decimal digits per 4-byte integer, rather than 5 as in PL/I, which has unsigned integer as a standard data type. In any case, this should likely work “out of the box” so give it a try first!
Be prepared to wait quite a while for a large number of digits. 100,000 digits takes about
8 hours on a newer (circa 1995) MicroVAX 3100/80.
This is a FORTRAN port of an older program I wrote for this purpose in PL/I.
K. McQuiggin