paranoia

c version of William M. Kahan's paranoia program to check CPU floating-point math for correctness

William M. Kahan is the father of the IEEE-754 standard for floating-point arithmetic in modern computers. On the 19th of April, 1983, (41 days before my birth) Kahan released a MS BASIC program to check for the correctness of the floating-point arithmetic implementation on any given machine. This original program was translated into Pascal by B. A. Wichmann on 18 Jan. 1985 and subsequently into c by David M. Gay (AT&T Bell Labs) & Thos Sumner (UCSF) between 1985 and 1986. This is the version provided here along with a convenient makefile (adapted from one written by Andrey Vladimirov of Colfax International) to compile and run the program.

To make and run paranoia on the CPU, type run-cpu. To make and run paranoia on an Intel Xeon Phi, type run-mic.

Read the original Kahan article in the 1985 issue of BYTE magazine for more details. Another classic read is David Goldberg's What Every Computer Scientist Should Know About Floating-Point Arithmetic.