android-calculatorpp/src/org/solovyev/util/math/MathUtils.java
2011-09-11 17:17:20 +04:00

103 lines
2.6 KiB
Java

package org.solovyev.util.math;
import org.jetbrains.annotations.NotNull;
import java.util.List;
public class MathUtils {
public static final float MIN_AMOUNT = 0.05f;
public static double round(@NotNull Double value, int numberOfFractionDigits) {
double roundFactor = Math.pow(10, numberOfFractionDigits);
if (value < Double.MAX_VALUE / roundFactor) {
return ((double)Math.round(value * roundFactor)) / roundFactor;
} else {
return value;
}
}
public static float getDistance(@NotNull Point2d startPoint,
@NotNull Point2d endPoint) {
return getNorm(subtract(endPoint, startPoint));
}
public static Point2d subtract(@NotNull Point2d p1, @NotNull Point2d p2) {
return new Point2d(p1.getX() - p2.getX(), p1.getY() - p2.getY());
}
public static Point2d sum(@NotNull Point2d p1, @NotNull Point2d p2) {
return new Point2d(p1.getX() + p2.getX(), p1.getY() + p2.getY());
}
public static float getNorm(@NotNull Point2d point) {
return (float) Math.pow(
Math.pow(point.getX(), 2) + Math.pow(point.getY(), 2), 0.5);
}
public static float getAngle(@NotNull Point2d startPoint,
@NotNull Point2d axisEndPoint, @NotNull Point2d endPoint) {
final Point2d axisVector = subtract(axisEndPoint, startPoint);
final Point2d vector = subtract(endPoint, startPoint);
double a_2 = Math.pow(getDistance(vector, axisVector), 2);
double b = getNorm(vector);
double b_2 = Math.pow(b, 2);
double c = getNorm(axisVector);
double c_2 = Math.pow(c, 2);
return (float) Math.acos((-a_2 + b_2 + c_2) / (2 * b * c));
}
public static double countMean(@NotNull List<Double> objects) {
double sum = 0d;
for (Double object : objects) {
sum += object;
}
return objects.size() == 0 ? 0d : (sum / objects.size());
}
public static double countStandardDeviation(@NotNull Double mean, @NotNull List<Double> objects) {
double sum = 0d;
for (Double object : objects) {
sum += Math.pow(object - mean, 2);
}
return objects.size() == 0 ? 0d : Math.sqrt(sum / objects.size());
}
public static StatData getStatData(@NotNull List<Double> objects) {
final double mean = countMean(objects);
final double standardDeviation = countStandardDeviation(mean, objects);
return new StatData(mean, standardDeviation);
}
public static class StatData {
private final double mean;
private final double standardDeviation;
public StatData(double mean, double standardDeviation) {
this.mean = mean;
this.standardDeviation = standardDeviation;
}
public double getMean() {
return mean;
}
public double getStandardDeviation() {
return standardDeviation;
}
}
}