geos::precision::CommonBits Class Reference

Determines the maximum number of common most-significant bits in the mantissa of one or numbers. More...

#include <CommonBits.h>

List of all members.

Public Member Functions

void add (double num)
double getCommon ()

Static Public Member Functions

static int64 signExpBits (int64 num)
 Computes the bit pattern for the sign and exponent of a double-precision number.
static int numCommonMostSigMantissaBits (int64 num1, int64 num2)
 This computes the number of common most-significant bits in the mantissas of two double-precision numbers.
static int64 zeroLowerBits (int64 bits, int nBits)
 Zeroes the lower n bits of a bitstring.
static int getBit (int64 bits, int i)
 Extracts the i'th bit of a bitstring.


Detailed Description

Determines the maximum number of common most-significant bits in the mantissa of one or numbers.

Can be used to compute the double-precision number which is represented by the common bits. If there are no common bits, the number computed is 0.0.


Member Function Documentation

static int64 geos::precision::CommonBits::signExpBits ( int64  num  )  [static]

Computes the bit pattern for the sign and exponent of a double-precision number.

Parameters:
num 
Returns:
the bit pattern for the sign and exponent

static int geos::precision::CommonBits::numCommonMostSigMantissaBits ( int64  num1,
int64  num2 
) [static]

This computes the number of common most-significant bits in the mantissas of two double-precision numbers.

It does not count the hidden bit, which is always 1. It does not determine whether the numbers have the same exponent - if they do not, the value computed by this function is meaningless.

Parameters:
db 
Returns:
the number of common most-significant mantissa bits

static int64 geos::precision::CommonBits::zeroLowerBits ( int64  bits,
int  nBits 
) [static]

Zeroes the lower n bits of a bitstring.

Parameters:
bits the bitstring to alter
i the number of bits to zero
Returns:
the zeroed bitstring

static int geos::precision::CommonBits::getBit ( int64  bits,
int  i 
) [static]

Extracts the i'th bit of a bitstring.

Parameters:
bits the bitstring to extract from
i the bit to extract
Returns:
the value of the extracted bit


The documentation for this class was generated from the following file:
Generated on Fri Mar 27 04:54:03 2009 for GEOS by  doxygen 1.5.4