Returns the hyperbolic cosine of a double. - Java java.lang

Java examples for java.lang:Math Trigonometric Function

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Description

Returns the hyperbolic cosine of a double.

Demo Code

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//package com.java2s;

public class Main {
    /**
     * Returns the hyperbolic cosine of a double.
     * 
     * @param x
     *            A double value.
     * @return The hyperbolic cosine of x. If x is NaN, the result is NaN.
     */
    static public double cosh(double x) {
        double ans;
        double y = Math.exp(Math.abs(x));

        if (Double.isNaN(x)) {
            ans = Double.NaN;
        } else if (Double.isInfinite(x)) {
            ans = x;
        } else if (y < 94906265.62) {
            // 94906265.62 = 1.0/Math.sqrt(EPSILON_SMALL)
            ans = 0.5 * (y + 1.0 / y);
        } else {
            ans = 0.5 * y;
        }
        return ans;
    }
}

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