PARANOIA
Kahan's Floating Point Test Program

PARANOIA is a FORTRAN77 program which checks properties of a computer's arithmetic.

PARANOIA is a version of a program, originally written in BASIC (!) by Professor W M Kahan, which tests the properties of the floating point arithmetic used on a computer. It is a more ambitious test than that carried out by MACHAR.

The original, true, correct version of PARANOIA is available in the PARANOIA subdirectory of the NETLIB web site.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

PARANOIA is available in a C version and a FORTRAN77 version and a FORTRAN90 version.

Related Data and Programs:

MACHAR, a FORTRAN77 library which computes the appropriate values of machine constants for a given machine.

MACHINE, a FORTRAN77 library which store the appropriate values of machine constants for a given machine.

Reference:

• Richard Karpinski,
  Paranoia: A floating-point benchmark,
  Byte Magazine,
  Volume 10, Number 2, February 1985, pages 223-235.

Source Code:

• paranoia.f, the source code;
• paranoia.sh, commands to compile and load the source code;

Examples and Tests:

• paranoia_input.txt, a file that can be used as input to PARANOIA for a noninteractive run.
• paranoia_output.txt, the output file;

List of Routines:

• PARANOIA investigates floating point arithmetic.
• COMMUTE tests for commutative multiplication.
• RANDOM computes a "somewhat" randomized number.
• EXTRA tests for extra precision in subexpressions.
• GUARD checks for guard digits and normalization in subtraction.
• INTRO prints the introduction.
• LOGIT writes information to a checkpoint file.
• CMPXY compares X and Y=Z**Q for equality.
• PRT2 prints N, and pauses if N > 0.
• PWRCMP compares Z**I with Z*Z*...*Z.
• PRTCNT prints the number of discrepancies.
• BADSQR reports on errors involving square of the square root.
• OVERF tests overflow threshholds.
• PAGE waits for the user to press RETURN.
• PARTUF tests for partial underflow.
• POWER tests the calculation of Y**X.
• RADX finds the radix and precision.
• ROUND tests rounding in multiplication, division, addition and subtraction.
• SMLINT performs tests on small integers.
• SQUARE tests the square root function.
• SQERR asseses error in SQRT ( X * X ) - X.
• NEWD updates D and Z.
• SQRTDX tests the SQRT function.
• UNDERF tests underflow threshholds.
• ZEROS investigates division by zero.
• BADMIL reports on unrecognizable milestones.
• IDINT converts a double precision value to an integer.

You can go up one level to the FORTRAN77 source codes.