Get the next machine representable number after a number, moving in the direction of another number. : double « Data Type « Java

Get the next machine representable number after a number, moving in the direction of another number.


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 *  distributed under the License is distributed on an "AS IS" BASIS,
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public class Main {

   * Get the next machine representable number after a number, moving
   * in the direction of another number.
   * <p>
   * If <code>direction</code> is greater than or equal to<code>d</code>,
   * the smallest machine representable number strictly greater than
   * <code>d</code> is returned; otherwise the largest representable number
   * strictly less than <code>d</code> is returned.</p>
   * <p>
   * If <code>d</code> is NaN or Infinite, it is returned unchanged.</p>
   * @param d base number
   * @param direction (the only important thing is whether
   * direction is greater or smaller than d)
   * @return the next machine representable number in the specified direction
   * @since 1.2
  public static double nextAfter(double d, double direction) {

      // handling of some important special cases
      if (Double.isNaN(d) || Double.isInfinite(d)) {
              return d;
      } else if (d == 0) {
              return (direction < 0) ? -Double.MIN_VALUE : Double.MIN_VALUE;
      // special cases MAX_VALUE to infinity and  MIN_VALUE to 0
      // are handled just as normal numbers

      // split the double in raw components
      long bits     = Double.doubleToLongBits(d);
      long sign     = bits & 0x8000000000000000L;
      long exponent = bits & 0x7ff0000000000000L;
      long mantissa = bits & 0x000fffffffffffffL;

      if (d * (direction - d) >= 0) {
              // we should increase the mantissa
              if (mantissa == 0x000fffffffffffffL) {
                      return Double.longBitsToDouble(sign |
                                      (exponent + 0x0010000000000000L));
              } else {
                      return Double.longBitsToDouble(sign |
                                      exponent | (mantissa + 1));
      } else {
              // we should decrease the mantissa
              if (mantissa == 0L) {
                      return Double.longBitsToDouble(sign |
                                      (exponent - 0x0010000000000000L) |
              } else {
                      return Double.longBitsToDouble(sign |
                                      exponent | (mantissa - 1));




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