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MATH-740

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Grabbing a few percents performance for "log".


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1369506 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Gilles Sadowski 2012-08-04 23:11:45 +00:00
parent bfdf1c44af
commit b6e62ab83a
1 changed files with 17 additions and 13 deletions
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30
src/main/java/org/apache/commons/math3/util/FastMath.java
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@ -1145,7 +1145,7 @@ public class FastMath {
/* Normalize the subnormal number. */
bits <<= 1;
while ( (bits & 0x0010000000000000L) == 0) {
exp--;
--exp;
bits <<= 1;
}
}
@ -1165,8 +1165,9 @@ public class FastMath {
xa = aa;
xb = ab;
double ya = LN_QUICK_COEF[LN_QUICK_COEF.length-1][0];
double yb = LN_QUICK_COEF[LN_QUICK_COEF.length-1][1];
final double[] lnCoef_last = LN_QUICK_COEF[LN_QUICK_COEF.length - 1];
double ya = lnCoef_last[0];
double yb = lnCoef_last[1];
for (int i = LN_QUICK_COEF.length - 2; i >= 0; i--) {
/* Multiply a = y * x */
@ -1178,8 +1179,9 @@ public class FastMath {
yb = aa - ya + ab;
/* Add a = y + lnQuickCoef */
aa = ya + LN_QUICK_COEF[i][0];
ab = yb + LN_QUICK_COEF[i][1];
final double[] lnCoef_i = LN_QUICK_COEF[i];
aa = ya + lnCoef_i[0];
ab = yb + lnCoef_i[1];
/* Split y = a */
tmp = aa * HEX_40000000;
ya = aa + tmp - tmp;
@ -1199,7 +1201,7 @@ public class FastMath {
}
// lnm is a log of a number in the range of 1.0 - 2.0, so 0 <= lnm < ln(2)
double lnm[] = lnMant.LN_MANT[(int)((bits & 0x000ffc0000000000L) >> 42)];
final double[] lnm = lnMant.LN_MANT[(int)((bits & 0x000ffc0000000000L) >> 42)];
/*
double epsilon = x / Double.longBitsToDouble(bits & 0xfffffc0000000000L);
@ -1210,7 +1212,7 @@ public class FastMath {
// y is the most significant 10 bits of the mantissa
//double y = Double.longBitsToDouble(bits & 0xfffffc0000000000L);
//double epsilon = (x - y) / y;
double epsilon = (bits & 0x3ffffffffffL) / (TWO_POWER_52 + (bits & 0x000ffc0000000000L));
final double epsilon = (bits & 0x3ffffffffffL) / (TWO_POWER_52 + (bits & 0x000ffc0000000000L));
double lnza = 0.0;
double lnzb = 0.0;
@ -1224,14 +1226,15 @@ public class FastMath {
double xb = ab;
/* Need a more accurate epsilon, so adjust the division. */
double numer = bits & 0x3ffffffffffL;
double denom = TWO_POWER_52 + (bits & 0x000ffc0000000000L);
final double numer = bits & 0x3ffffffffffL;
final double denom = TWO_POWER_52 + (bits & 0x000ffc0000000000L);
aa = numer - xa*denom - xb * denom;
xb += aa / denom;
/* Remez polynomial evaluation */
double ya = LN_HI_PREC_COEF[LN_HI_PREC_COEF.length-1][0];
double yb = LN_HI_PREC_COEF[LN_HI_PREC_COEF.length-1][1];
final double[] lnCoef_last = LN_HI_PREC_COEF[LN_HI_PREC_COEF.length-1];
double ya = lnCoef_last[0];
double yb = lnCoef_last[1];
for (int i = LN_HI_PREC_COEF.length - 2; i >= 0; i--) {
/* Multiply a = y * x */
@ -1243,8 +1246,9 @@ public class FastMath {
yb = aa - ya + ab;
/* Add a = y + lnHiPrecCoef */
aa = ya + LN_HI_PREC_COEF[i][0];
ab = yb + LN_HI_PREC_COEF[i][1];
final double[] lnCoef_i = LN_HI_PREC_COEF[i];
aa = ya + lnCoef_i[0];
ab = yb + lnCoef_i[1];
/* Split y = a */
tmp = aa * HEX_40000000;
ya = aa + tmp - tmp;