org.apache.lucene.util

Class SmallFloat


public class SmallFloat
extends Object

Floating point numbers smaller than 32 bits.
Version:
$Id$
Author:
yonik

Method Summary

static float
byte315ToFloat(byte b)
byteToFloat(b, mantissaBits=3, zeroExponent=15)
static float
byte52ToFloat(byte b)
byteToFloat(b, mantissaBits=5, zeroExponent=2)
static float
byteToFloat(byte b, int numMantissaBits, int zeroExp)
Converts an 8 bit float to a 32 bit float.
static byte
floatToByte(float f, int numMantissaBits, int zeroExp)
Converts a 32 bit float to an 8 bit float.
static byte
floatToByte315(float f)
floatToByte(b, mantissaBits=3, zeroExponent=15)
smallest non-zero value = 5.820766E-10
largest value = 7.5161928E9
epsilon = 0.125
static byte
floatToByte52(float f)
floatToByte(b, mantissaBits=5, zeroExponent=2)
smallest nonzero value = 0.033203125
largest value = 1984.0
epsilon = 0.03125

Method Details

byte315ToFloat

public static float byte315ToFloat(byte b)
byteToFloat(b, mantissaBits=3, zeroExponent=15)

byte52ToFloat

public static float byte52ToFloat(byte b)
byteToFloat(b, mantissaBits=5, zeroExponent=2)

byteToFloat

public static float byteToFloat(byte b,
                                int numMantissaBits,
                                int zeroExp)
Converts an 8 bit float to a 32 bit float.

floatToByte

public static byte floatToByte(float f,
                               int numMantissaBits,
                               int zeroExp)
Converts a 32 bit float to an 8 bit float.
Values less than zero are all mapped to zero.
Values are truncated (rounded down) to the nearest 8 bit value.
Values between zero and the smallest representable value are rounded up.
Parameters:
f - the 32 bit float to be converted to an 8 bit float (byte)
numMantissaBits - the number of mantissa bits to use in the byte, with the remainder to be used in the exponent
zeroExp - the zero-point in the range of exponent values
Returns:
the 8 bit float representation

floatToByte315

public static byte floatToByte315(float f)
floatToByte(b, mantissaBits=3, zeroExponent=15)
smallest non-zero value = 5.820766E-10
largest value = 7.5161928E9
epsilon = 0.125

floatToByte52

public static byte floatToByte52(float f)
floatToByte(b, mantissaBits=5, zeroExponent=2)
smallest nonzero value = 0.033203125
largest value = 1984.0
epsilon = 0.03125

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