Returns the smallest (closest to negative infinity)
{@code double} value that is greater than or equal to the
argument and is equal to a mathematical integer. Special cases:
<ul><li>If the argument value is already equal to a
mathematical integer, then the result is the same as the
argument. <li>If the argument is NaN or an infinity or
positive zero or negative zero, then the result is the same as
the argument. <li>If the argument value is less than zero but
greater than -1.0, then the result is negative zero.</ul> Note
that the value of {@code Math.ceil(x)} is exactly the
value of {@code -Math.floor(-x)}.
@param a a value.
@return the smallest (closest to negative infinity)
floating-point value that is greater than or equal to
the argument and is equal to a mathematical integer.
Returns the smallest (closest to negative infinity) {@code double} value that is greater than or equal to the argument and is equal to a mathematical integer. Special cases: <ul><li>If the argument value is already equal to a mathematical integer, then the result is the same as the argument. <li>If the argument is NaN or an infinity or positive zero or negative zero, then the result is the same as the argument. <li>If the argument value is less than zero but greater than -1.0, then the result is negative zero.</ul> Note that the value of {@code Math.ceil(x)} is exactly the value of {@code -Math.floor(-x)}.