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Range.cc
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1996-12-20
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/*
Copyright (C) 1996 John W. Eaton
This file is part of Octave.
Octave is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.
Octave is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with Octave; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#if defined (__GNUG__)
#pragma implementation
#endif
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <cfloat>
#include <climits>
#include <cmath>
#include <iostream.h>
#include "Range.h"
#include "dMatrix.h"
#include "lo-mappers.h"
#include "lo-utils.h"
bool
Range::all_elements_are_ints (void) const
{
// If the base and increment are ints, the final value in the range
// will also be an integer, even if the limit is not.
return (! (xisnan (rng_base) || xisnan (rng_inc))
&& (double) NINT (rng_base) == rng_base
&& (double) NINT (rng_inc) == rng_inc);
}
Matrix
Range::matrix_value (void) const
{
Matrix retval;
if (rng_nelem > 0)
{
retval.resize (1, rng_nelem);
double b = rng_base;
double increment = rng_inc;
for (int i = 0; i < rng_nelem; i++)
retval.elem (0, i) = b + i * increment;
}
return retval;
}
// NOTE: max and min only return useful values if nelem > 0.
double
Range::min (void) const
{
double retval = 0.0;
if (rng_nelem > 0)
{
if (rng_inc > 0)
retval = rng_base;
else
retval = rng_base + (rng_nelem - 1) * rng_inc;
}
return retval;
}
double
Range::max (void) const
{
double retval = 0.0;
if (rng_nelem > 0)
{
if (rng_inc > 0)
retval = rng_base + (rng_nelem - 1) * rng_inc;
else
retval = rng_base;
}
return retval;
}
void
Range::sort (void)
{
if (rng_base > rng_limit && rng_inc < 0.0)
{
double tmp = rng_base;
rng_base = min ();
rng_limit = tmp;
rng_inc = -rng_inc;
}
}
void
Range::print_range (void)
{
cerr << "Range: rng_base = " << rng_base
<< " rng_limit " << rng_limit
<< " rng_inc " << rng_inc
<< " rng_nelem " << rng_nelem << "\n";
}
ostream&
operator << (ostream& os, const Range& a)
{
double b = a.base ();
double increment = a.inc ();
int num_elem = a.nelem ();
for (int i = 0; i < num_elem; i++)
os << b + i * increment << " ";
os << "\n";
return os;
}
istream&
operator >> (istream& is, Range& a)
{
is >> a.rng_base;
if (is)
{
is >> a.rng_limit;
if (is)
{
is >> a.rng_inc;
a.rng_nelem = a.nelem_internal ();
}
}
return is;
}
Range
operator - (const Range& r)
{
return Range (-r.base (), -r.limit (), -r.inc ());
}
// C See Knuth, Art Of Computer Programming, Vol. 1, Problem 1.2.4-5.
// C
// C===Tolerant FLOOR function.
// C
// C X - is given as a Double Precision argument to be operated on.
// C It is assumed that X is represented with M mantissa bits.
// C CT - is given as a Comparison Tolerance such that
// C 0.LT.CT.LE.3-SQRT(5)/2. If the relative difference between
// C X and A whole number is less than CT, then TFLOOR is
// C returned as this whole number. By treating the
// C floating-point numbers as a finite ordered set note that
// C the heuristic EPS=2.**(-(M-1)) and CT=3*EPS causes
// C arguments of TFLOOR/TCEIL to be treated as whole numbers
// C if they are exactly whole numbers or are immediately
// C adjacent to whole number representations. Since EPS, the
// C "distance" between floating-point numbers on the unit
// C interval, and M, the number of bits in X'S mantissa, exist
// C on every floating-point computer, TFLOOR/TCEIL are
// C consistently definable on every floating-point computer.
// C
// C For more information see the following references:
// C (1) P. E. Hagerty, "More On Fuzzy Floor And Ceiling," APL QUOTE
// C QUAD 8(4):20-24, June 1978. Note that TFLOOR=FL5.
// C (2) L. M. Breed, "Definitions For Fuzzy Floor And Ceiling", APL
// C QUOTE QUAD 8(3):16-23, March 1978. This paper cites FL1 through
// C FL5, the history of five years of evolutionary development of
// C FL5 - the seven lines of code below - by open collaboration
// C and corroboration of the mathematical-computing community.
// C
// C Penn State University Center for Academic Computing
// C H. D. Knoble - August, 1978.
static inline double
tfloor (double x, double ct)
{
// C---------FLOOR(X) is the largest integer algebraically less than
// C or equal to X; that is, the unfuzzy FLOOR function.
// DINT (X) = X - DMOD (X, 1.0);
// FLOOR (X) = DINT (X) - DMOD (2.0 + DSIGN (1.0, X), 3.0);
// C---------Hagerty's FL5 function follows...
double q = 1.0;
if (x < 0.0)
q = 1.0 - ct;
double rmax = q / (2.0 - ct);
double t1 = 1.0 + floor (x);
t1 = (ct / q) * (t1 < 0.0 ? -t1 : t1);
t1 = rmax < t1 ? rmax : t1;
t1 = ct > t1 ? ct : t1;
t1 = floor (x + t1);
if (x <= 0.0 || (t1 - x) < rmax)
return t1;
else
return t1 - 1.0;
}
static inline double
tceil (double x, double ct)
{
return -tfloor (-x, ct);
}
static inline double
round (double x, double ct)
{
return tfloor (x+0.5, ct);
}
int
Range::nelem_internal (void) const
{
double ct = 3.0 * DBL_EPSILON;
double tmp = tfloor ((rng_limit - rng_base + rng_inc) / rng_inc, ct);
int n_intervals = (int) (tmp > 0.0 ? tmp : 0);
return (n_intervals >= INT_MAX - 1) ? -1 : n_intervals;
}
/*
;;; Local Variables: ***
;;; mode: C++ ***
;;; End: ***
*/