Returns the factorial of an integer. - Java java.lang

Java examples for java.lang:Math Number

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Description

Returns the factorial of an integer.

Demo Code

/*/*from  w  w w.  j av  a2s . com*/
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//package com.java2s;

public class Main {
    /**
     * Returns the factorial of an integer.
     * 
     * @param n
     *            An integer value.
     * @return The factorial of n, n!. If x is negative, the result is NaN.
     */
    static public double fact(int n) {
        double ans = 1;

        if (Double.isNaN(n) || n < 0) {
            ans = Double.NaN;
        } else if (n > 170) {
            // The 171! is too large to fit in a double.
            ans = Double.POSITIVE_INFINITY;
        } else {
            for (int k = 2; k <= n; k++)
                ans *= k;
        }
        return ans;
    }
}

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