Support MPFR floats in numkondov1.4

Remove '-D' option (error tolerance) in numkondo

1 files changed, 21 insertions, 7 deletions

diff --git a/man/numkondo.1 b/man/numkondo.1
index e7b4807..3af84df 100644
--- a/man/numkondo.1
+++ b/man/numkondo.1
@@ -1,5 +1,5 @@
-.Dd $Mdocdate: April 14 2015 $
-.Dt numkondo 1.3.1
+.Dd $Mdocdate: September 22 2015 $
+.Dt numkondo 1.4
 .Os
 .Sh NAME
 .Nm numkondo
@@ -8,8 +8,9 @@
 .Nm
 .Op Fl F
 .Op Fl N Ar niter
-.Op Fl D Ar tolerance
 .Op Fl I Ar initial_condition
+.Op Fl P Ar precision
+.Op Fl E Ar max_exponent
 .Op Ar config_file
 .Pp
 .Nm
@@ -44,12 +45,12 @@ as well as the following pre-processors, which generate configuration files for
 Number of iterations
 .It Fl F
 Only print the last step of the computation, with full precision. The output can be used as an initial condition for further iterations.
-.It Fl D Ar tolerance
-If this option is provided, any number smaller than
-.Ar tolerance
-is set to 0.
 .It Fl I Ar initial_condition
 Set the initial condition from the command-line (overrides the initial condition in the configuration file). The format is the same as the '#!initial_configuration' entry, see below.
+.It Fl P Ar precision
+Number of bits used for the significand of numerical values (see the NUMERICAL PRECISION section). If this option is specified, then numerical values are represented as MPFR floats instead of long doubles, which requires more computating time.
+.It Fl E Ar max_exponent
+Largest allowed value for the exponent of numerical values (see the NUMERICAL PRECISION section). If this option is specified, then numerical values are represented as MPFR floats instead of long doubles, which requires more computating time.
 .It Fl v
 Print version information and exit.
 .El
@@ -145,6 +146,19 @@ If the '-F' flag is provided,
 .Nm
 prints the last step of the iteration to stdout in a format that can be re-used as an initial condition for subsequent iterations.
 .Pp
+.Sh NUMERICAL PRECISION
+Numerical values are represented as floating point numbers, which consist in a significand (or mantissa) and an exponent. The number is given by
+.D1 significand * 2^exponent
+.Pp
+If neither the '-P' nor the '-E' flags are specified, then numerical values are implemented using the 'long double' type, which allocates 64 bits to the significand and 15 to the exponent (this may change depending on the implementation of the C compiler used to compile
+.Nm ) .
+Numbers are therefore accurate to 19 decimal places, and the exponent must be in the interval [-16382 , 16383].
+.Pp
+If one of the '-P' or '-E' flags are specified, then numerical values are implemented using the GNU MPFR library. The number of bits allocated to the significand and exponent can be set by the '-P' and '-E' flags, within the limits set by the MPFR library. These values depend on the implementation of the library. On 64-bit systems, the maximal precision and maximal value of the exponent should be of the order of 2^63 and 2^62 respectively.
+.Pp
+Note that using MPFR floats increases the computing time required to run
+.Nm
+.Pp
 .Sh RETURN CODE
 .Nm
 returns 0 on success and -1 on error.