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 floatbyte315ToFloat(byte b)
byteToFloat(b, mantissaBits=3, zeroExponent=15)
static floatbyte52ToFloat(byte b)
byteToFloat(b, mantissaBits=5, zeroExponent=2)
static floatbyteToFloat(byte b, int numMantissaBits, int zeroExp)
Converts an 8 bit float to a 32 bit float.
static bytefloatToByte(float f, int numMantissaBits, int zeroExp)
Converts a 32 bit float to an 8 bit float.
static bytefloatToByte315(float f)
floatToByte(b, mantissaBits=3, zeroExponent=15)
smallest non-zero value = 5.820766E-10
largest value = 7.5161928E9
epsilon = 0.125
static bytefloatToByte52(float f)
floatToByte(b, mantissaBits=5, zeroExponent=2)
smallest nonzero value = 0.033203125
largest value = 1984.0
epsilon = 0.03125

Method Detail

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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