This page contains some easy C source code for constants computation.

1  Classical approaches

• Computation of p : piclassic.c implements a classical approach based on Machin like formulae to compute p (see The constant p).
• Computation of e : eclassic.c implements the classical method described in The constant e.
• Computation of Ö2 : sqrt2series.c implements a classical approach on an accelerated version of the Ö2 series (see The square root of 2).
• Computation of log(2) : log2classic.c implements a classical approach described in The logarithmic constant log(2).

Any comments are welcome : sebah.pascal@fnac.net.

2  Fast approaches

The following C files contain a short and very basic approach of the binary splitting method to compute e (see the algorithm description in Binary splitting method).

• FFT files FFT.c, FFT.h ;
• Large integers library BigInt.c, BigInt.h ;
• Binary splitting technique to compute e : e.c.

Those C codes are just learning programs to permit a better understanding of the techniques used (FFT and binary splitting). Many speed or memory optimizations can be done. A really efficient program (such as the one used for PiFast for example) could save a factor of order 10 for the time and 4 for the memory.

The program runs in quasi-linear time. Here are the timings on my machine (PentiumII 350) :

Any comments are welcome : xgourdon@yahoo.fr,

mathematical constants and computation