未为类型Math定义IEEEremainder（double，double）

Question

I am trying to use java.lang.Math.IEEEremainder(double f1, double f2) in GWT. But I got below exception.

[ERROR] Line 1119: The method IEEEremainder(double, double) is undefined for the type Math

I attempted to execute this code : angle = Math.IEEEremainder(angle, 360.0);

How to solve this issue in GWT?. If its not solve then what would be the alternative way to achieve the same functionality of Math.IEEEremainder this method.

Answer 1

According to the JRE Emulation this function is not supported in GWT.

So if you really need it and can't work around it, you will need to implement it yourself.

If I understand it correctly, you are trying to limit the angle to 360 degrees. You could achieve that with this code:

/**
 * Normalize a degree value.
 * @param d value
 * @return 0<=value<=360
 */
public static double normalizeDegrees(double d)
{
    while (d < 0)
    {
        d += 360;
    }
    while (d > 360)
    {
        d -= 360;
    }
    return d;
}

If you just got positive numbers, you can even skip the upper while -Block.

Answer 2

If you really need to have the IEEEremainder method in GWT, implement it like that:

/**
 * Computes the remainder operation on two arguments as prescribed by the IEEE 754 standard. The remainder value is
 * mathematically equal to <code>f1&nbsp;-&nbsp;f2</code>&nbsp;&times;&nbsp;<i>n</i>, where <i>n</i> is the
 * mathematical integer closest to the exact mathematical value of the quotient {@code f1/f2}, and if two
 * mathematical integers are equally close to {@code f1/f2}, then <i>n</i> is the integer that is even. If the
 * remainder is zero, its sign is the same as the sign of the first argument. Special cases:
 * <ul>
 * <li>If either argument is NaN, or the first argument is infinite, or the second argument is positive zero or
 * negative zero, then the result is NaN.
 * <li>If the first argument is finite and the second argument is infinite, then the result is the same as the first
 * argument.
 * </ul>
 * @param f1 the dividend.
 * @param f2 the divisor.
 * @return the remainder when {@code f1} is divided by {@code f2}.
 */
public static double IEEEremainder(double f1, double f2)
{
    double div = Math.round(f1 / f2);
    return f1 - (div * f2);
}

(I added this as a new comment to show the syntax highlighting).