FastMath { public static double toDegrees(double x) { if (Double.isInfinite(x) || x == 0.0) { return x; } final double facta = 57.2957763671875; final double factb = 3.145894820876798E-6; double xa = doubleHighPart(x); double xb = x - xa; return xb * factb + xb * facta + xa * factb + xa * facta; } private  FastMath(); static double sqrt(final double a); static double cosh(double x); static double sinh(double x); static double tanh(double x); static double acosh(final double a); static double asinh(double a); static double atanh(double a); static double signum(final double a); static float signum(final float a); static double nextUp(final double a); static float nextUp(final float a); static double nextDown(final double a); static float nextDown(final float a); static double random(); static double exp(double x); static double expm1(double x); static double log(final double x); static double log1p(final double x); static double log10(final double x); static double log(double base, double x); static double pow(double x, double y); static double pow(double d, int e); static double sin(double x); static double cos(double x); static double tan(double x); static double atan(double x); static double atan2(double y, double x); static double asin(double x); static double acos(double x); static double cbrt(double x); static double toRadians(double x); static double toDegrees(double x); static int abs(final int x); static long abs(final long x); static float abs(final float x); static double abs(double x); static double ulp(double x); static float ulp(float x); static double scalb(final double d, final int n); static float scalb(final float f, final int n); static double nextAfter(double d, double direction); static float nextAfter(final float f, final double direction); static double floor(double x); static double ceil(double x); static double rint(double x); static long round(double x); static int round(final float x); static int min(final int a, final int b); static long min(final long a, final long b); static float min(final float a, final float b); static double min(final double a, final double b); static int max(final int a, final int b); static long max(final long a, final long b); static float max(final float a, final float b); static double max(final double a, final double b); static double hypot(final double x, final double y); static double IEEEremainder(double dividend, double divisor); static int toIntExact(final long n); static int incrementExact(final int n); static long incrementExact(final long n); static int decrementExact(final int n); static long decrementExact(final long n); static int addExact(final int a, final int b); static long addExact(final long a, final long b); static int subtractExact(final int a, final int b); static long subtractExact(final long a, final long b); static int multiplyExact(final int a, final int b); static long multiplyExact(final long a, final long b); static int floorDiv(final int a, final int b); static long floorDiv(final long a, final long b); static int floorMod(final int a, final int b); static long floorMod(final long a, final long b); static double copySign(double magnitude, double sign); static float copySign(float magnitude, float sign); static int getExponent(final double d); static int getExponent(final float f); static void main(String[] a); static final double PI; static final double E; }
@Test public void testToDegrees() { double maxerrulp = 0.0; for (int i = 0; i < NUMBER_OF_TRIALS; i++) { double x = generator.nextDouble(); double tst = field.newDfp(x).multiply(180).divide(field.getPi()).toDouble(); double ref = FastMath.toDegrees(x); double err = (tst - ref) / ref; if (err != 0) { double ulp = Math.abs(ref - Double.longBitsToDouble((Double.doubleToLongBits(ref) ^ 1))); double errulp = field.newDfp(tst).subtract(DfpMath.exp(field.newDfp(x)).subtract(field.getOne())).divide(field.newDfp(ulp)).toDouble(); maxerrulp = Math.max(maxerrulp, Math.abs(errulp)); } } Assert.assertTrue("toDegrees() had errors in excess of " + MAX_ERROR_ULP + " ULP", maxerrulp < MAX_ERROR_ULP); }