package edu.northwestern.at.utils.math;
/* Please see the license information at the end of this file. */
/** Machine-dependent arithmetic constants.
*/
public class Constants
{
/** Machine epsilon. Smallest double floating point number
* such that (1 + MACHEPS) > 1 .
*/
public static final double MACHEPS = determineMachineEpsilon();
/* Machine precision in decimal digits . */
public static final int MAXPREC = determineMaximumPrecision();
/** Maximum logarithm value. */
public static final double MAXLOG = 7.09782712893383996732E2;
/** Minimum logarithm value. */
public static final double MINLOG = -7.451332191019412076235E2;
/** Square root of 2. */
public static final double SQRT2 = Math.sqrt( 2.0D );
/** ( Square root of 2 ) / 2 . */
public static final double SQRT2DIV2 = SQRT2 / 2.0D;
/** Square root of PI. */
public static final double SQRTPI = Math.sqrt( Math.PI );
/** Natural log of PI. */
public static final double LNPI = Math.log( Math.PI );
/* LN(10) . */
public static final double LN10 = Math.log( 10.0D );
/* 1 / LN(10) */
// public static final double LN10INV = 1.0D / LN10;
public static final double LN10INV = 0.43429448190325182765D;
/* LN(2) */
public static final double LN2 = Math.log( 2.0D );
/* 1 / LN(2) */
public static final double LN2INV = 1.0D / LN2;
/* LN( Sqrt( 2 * PI ) ) */
public static final double LNSQRT2PI =
Math.log( Math.sqrt( 2.0D * Math.PI ) );
/** Determine machine epsilon.
*
* @return The machine epsilon as a double.
* The machine epsilon MACHEPS is the
* smallest number such that (1 + MACHEPS) == 1 .
*/
public static double determineMachineEpsilon()
{
double d1 = 1.3333333333333333D;
double d3;
double d4;
for( d4 = 0.0D; d4 == 0.0D; d4 = Math.abs( d3 - 1.0D ) )
{
double d2 = d1 - 1.0D;
d3 = d2 + d2 + d2;
}
return d4;
}
/** Determine maximum double floating point precision.
*
* @return Maximum number of digits of precision
* for double precision floating point.
*/
public static int determineMaximumPrecision()
{
// Get machine epsilon.
double macheps = determineMachineEpsilon();
// Maximum digits of precision
// is given by the negative of
// of the base 10 exponent of
// of the machine precision.
double digits =
ArithUtils.trunc(
Math.log( macheps ) / Math.log( 10.0D ) );
return -new Long( Math.round( digits ) ).intValue();
}
/** This class is non-instantiable but inheritable.
*/
protected Constants()
{
}
}
/*
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Northwestern University
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