Returns the inverse (arc) hyperbolic cosine of a double. - Java java.lang

Java examples for java.lang:Math Trigonometric Function

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Description

Returns the inverse (arc) hyperbolic cosine of a double.

Demo Code

/*/*from   w ww. jav  a 2s .  c  om*/
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 * granted by Visual Numerics, Inc., provided that the copyright notice
 * above and the following warranty disclaimer are preserved in human
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 * "AS IS", with NO WARRANTY.  TO THE EXTENT PERMITTED BY LAW, VNI
 * DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
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//package com.java2s;

public class Main {
    /**
     * Returns the inverse (arc) hyperbolic cosine of a double.
     * 
     * @param x
     *            A double value.
     * @return The arc hyperbolic cosine of x. If x is NaN or less than one, the
     *         result is NaN.
     */
    static public double acosh(double x) {
        double ans;

        if (Double.isNaN(x) || x < 1) {
            ans = Double.NaN;
        } else if (x < 94906265.62) {
            // 94906265.62 = 1.0/Math.sqrt(EPSILON_SMALL)
            ans = Math.log(x + Math.sqrt(x * x - 1.0));
        } else {
            ans = 0.69314718055994530941723212145818 + Math.log(x);
        }
        return ans;
    }
}

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