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Function `std.math.nextafter`

Calculates the next representable value after x in the direction of y.


						
				T nextafter(T)
				(
				

				  const T x,
				

				  const T y
				

				) pure nothrow @nogc @safe;

If y > x, the result will be the next largest floating-point value; if y < x, the result will be the next smallest value. If x == y, the result is y.

Remarks

This function is not generally very useful; it's almost always better to use the faster functions nextUp() or nextDown() instead.

The FE_INEXACT and FE_OVERFLOW exceptions will be raised if x is finite and the function result is infinite. The FE_INEXACT and FE_UNDERFLOW exceptions will be raised if the function value is subnormal, and x is not equal to y.

Example

float a = 1;
assert(is(typeof(nextafter(a, a)) == float));
assert(nextafter(a, a.infinity) > a);

double b = 2;
assert(is(typeof(nextafter(b, b)) == double));
assert(nextafter(b, b.infinity) > b);

real c = 3;
assert(is(typeof(nextafter(c, c)) == real));
assert(nextafter(c, c.infinity) > c);
}

//real nexttoward(real x, real y) { return core.stdc.math.nexttowardl(x, y); }

/**
* Returns the positive difference between x and y.
*
* Equivalent to `fmax(x-y, 0)`.
*
* Returns:
*      <table border="1" cellpadding="4" cellspacing="0">
              <caption>Special Values</caption>
              *      <tr><th scope="col">x, y</th>       <th scope="col">fdim(x, y)</th></tr>
*      <tr><td>x &gt; y</td>  <td>x - y</td></tr>
*      <tr><td>x &lt;= y</td> <td>+0.0</td></tr>
*      </table>
*/
real fdim(real x, real y) @safe pure nothrow @nogc { return (x > y) ? x - y : +0.0;

Authors

Walter Bright, Don Clugston, Conversion of CEPHES math library to D by Iain Buclaw and David Nadlinger

License

Boost License 1.0.