org.apache.lucene.util
Class SmallFloat

java.lang.Object
  org.apache.lucene.util.SmallFloat

public class SmallFloat
extends Object

Floating point numbers smaller than 32 bits.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Constructor Summary

SmallFloat()

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

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SmallFloat

public SmallFloat()

Method Detail

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

byteToFloat

public static float byteToFloat(byte b,
                                int numMantissaBits,
                                int zeroExp)

Converts an 8 bit float to a 32 bit float.

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

byte315ToFloat

public static float byte315ToFloat(byte b)

byteToFloat(b, mantissaBits=3, zeroExponent=15)

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

byte52ToFloat

public static float byte52ToFloat(byte b)

byteToFloat(b, mantissaBits=5, zeroExponent=2)