Struct std.math.FloatingPointControl

Change the IEEE754 floating-point rounding mode and the floating-point hardware exceptions.

By default, the rounding mode is roundToNearest and all hardware exceptions are disabled. For most applications, debugging is easier if the division by zero, overflow, and invalid operation exceptions are enabled. These three are combined into a severeExceptions value for convenience. Note in particular that if invalidException is enabled, a hardware trap will be generated whenever an uninitialized floating-point variable is used.

All changes are temporary. The previous state is restored at the end of the scope.

Properties

Methods

Example

{
    FloatingPointControl fpctrl;

    // Enable hardware exceptions for division by zero, overflow to infinity,
    // invalid operations, and uninitialized floating-point variables.
    fpctrl.enableExceptions(FloatingPointControl.severeExceptions);

    // This will generate a hardware exception, if x is a
    // default-initialized floating point variable:
    real x; // Add = 0 or even = real.nan to not throw the exception.
    real y = x * 3.0;

    // The exception is only thrown for default-uninitialized NaN-s.
    // NaN-s with other payload are valid:
    real z = y * real.nan; // ok

    // Changing the rounding mode:
    fpctrl.rounding = FloatingPointControl.roundUp;
    assert(rint(1.1) == 2);

    // The set hardware exceptions will be disabled when leaving this scope.
    // The original rounding mode will also be restored.
}

// Ensure previous values are returned:
assert(!FloatingPointControl.enabledExceptions);
assert(FloatingPointControl.rounding == FloatingPointControl.roundToNearest);
assert(rint(1.1) == 1);