# geos::index::quadtree::DoubleBits Class Reference

DoubleBits manipulates Double numbers by using bit manipulation and bit-field extraction. More...

`#include <DoubleBits.h>`

List of all members.

## Public Member Functions

| DoubleBits (double nx)
double | getDouble () const
int64 | biasedExponent () const
| Determines the exponent for the number.
int | getExponent () const
| Determines the exponent for the number.
void | zeroLowerBits (int nBits)
int | getBit (int i) const
int | numCommonMantissaBits (const DoubleBits &db) const
| This computes the number of common most-significant bits in the mantissa.
std::string | toString () const
| A representation of the Double bits formatted for easy readability.

## Static Public Member Functions

static double | powerOf2 (int exp)
static int | exponent (double d)
static double | truncateToPowerOfTwo (double d)
static std::string | toBinaryString (double d)
static double | maximumCommonMantissa (double d1, double d2)

## Static Public Attributes

static const int | EXPONENT_BIAS = 1023

## Detailed Description

DoubleBits manipulates Double numbers by using bit manipulation and bit-field extraction.

For some operations (such as determining the exponent) this is more accurate than using mathematical operations (which suffer from round-off error).

The algorithms and constants in this class apply only to IEEE-754 double-precision floating point format.

## Member Function Documentation

int geos::index::quadtree::DoubleBits::numCommonMantissaBits | ( | const DoubleBits & | db ) | const

This computes the number of common most-significant bits in the mantissa.

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

The documentation for this class was generated from the following file:

- DoubleBits.h