本文整理汇总了Java中org.apache.commons.math3.util.FastMath.signum方法的典型用法代码示例。如果您正苦于以下问题：Java FastMath.signum方法的具体用法？Java FastMath.signum怎么用？Java FastMath.signum使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类org.apache.commons.math3.util.FastMath的用法示例。
在下文中一共展示了FastMath.signum方法的3个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Java代码示例。
示例1: doSolve
import org.apache.commons.math3.util.FastMath; //导入方法依赖的package包/类
/**
* {@inheritDoc}
*/
@Override
protected double doSolve()
throws TooManyEvaluationsException,
NoBracketingException {
double min = getMin();
double max = getMax();
// [x1, x2] is the bracketing interval in each iteration
// x3 is the midpoint of [x1, x2]
// x is the new root approximation and an endpoint of the new interval
double x1 = min;
double y1 = computeObjectiveValue(x1);
double x2 = max;
double y2 = computeObjectiveValue(x2);
// check for zeros before verifying bracketing
if (y1 == 0) {
return min;
}
if (y2 == 0) {
return max;
}
verifyBracketing(min, max);
final double absoluteAccuracy = getAbsoluteAccuracy();
final double functionValueAccuracy = getFunctionValueAccuracy();
final double relativeAccuracy = getRelativeAccuracy();
double oldx = Double.POSITIVE_INFINITY;
while (true) {
// calculate the new root approximation
final double x3 = 0.5 * (x1 + x2);
final double y3 = computeObjectiveValue(x3);
if (FastMath.abs(y3) <= functionValueAccuracy) {
return x3;
}
final double delta = 1 - (y1 * y2) / (y3 * y3); // delta > 1 due to bracketing
final double correction = (FastMath.signum(y2) * FastMath.signum(y3)) *
(x3 - x1) / FastMath.sqrt(delta);
final double x = x3 - correction; // correction != 0
final double y = computeObjectiveValue(x);
// check for convergence
final double tolerance = FastMath.max(relativeAccuracy * FastMath.abs(x), absoluteAccuracy);
if (FastMath.abs(x - oldx) <= tolerance) {
return x;
}
if (FastMath.abs(y) <= functionValueAccuracy) {
return x;
}
// prepare the new interval for next iteration
// Ridders' method guarantees x1 < x < x2
if (correction > 0.0) { // x1 < x < x3
if (FastMath.signum(y1) + FastMath.signum(y) == 0.0) {
x2 = x;
y2 = y;
} else {
x1 = x;
x2 = x3;
y1 = y;
y2 = y3;
}
} else { // x3 < x < x2
if (FastMath.signum(y2) + FastMath.signum(y) == 0.0) {
x1 = x;
y1 = y;
} else {
x1 = x3;
x2 = x;
y1 = y3;
y2 = y;
}
}
oldx = x;
}
}
示例2: value
import org.apache.commons.math3.util.FastMath; //导入方法依赖的package包/类
/** {@inheritDoc} */
public double value(double x) {
return FastMath.signum(x);
}
示例3: signum
import org.apache.commons.math3.util.FastMath; //导入方法依赖的package包/类
/** {@inheritDoc}
* @since 3.2
*/
public DerivativeStructure signum() {
return new DerivativeStructure(compiler.getFreeParameters(),
compiler.getOrder(),
FastMath.signum(data[0]));
}