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std.math.IeeeFlags/ieeeFlags - multiple declarations

Function ieeeFlags

IeeeFlags ieeeFlags() pure nothrow @property @nogc @trusted;

Returns

snapshot of the current state of the floating-point status flags

Example

version (InlineAsm_X86_Any)
{
    resetIeeeFlags();
    real a = 3.5;

    a /= 0.0L;
    writeln(a); // real.infinity
    assert(ieeeFlags.divByZero);

    a *= 0.0L;
    assert(isNaN(a));
    assert(ieeeFlags.invalid);
}
}

/** Control the Floating point hardware

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 <i>division
by zero</i>, <i>overflow</i>, and <i>invalid operation</i> exceptions are enabled.
These three are combined into a <i>severeExceptions</i> value for convenience.
Note in particular that if <i>invalidException</i> 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.


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

// The set hardware exceptions and rounding modes will be disabled when // leaving this scope.

Struct IeeeFlags

IEEE exception status flags ('sticky bits')

struct IeeeFlags ;

These flags indicate that an exceptional floating-point condition has occurred. They indicate that a NaN or an infinity has been generated, that a result is inexact, or that a signalling NaN has been encountered. If floating-point exceptions are enabled (unmasked), a hardware exception will be generated instead of setting these flags.

Properties

NameTypeDescription
divByZero[get] boolAn infinity was generated by division by zero
divByZero[get] boolAn infinity was generated by division by zero
inexact[get] boolThe result cannot be represented exactly, so rounding occurred.
inexact[get] boolThe result cannot be represented exactly, so rounding occurred.
invalid[get] boolA machine NaN was generated.
invalid[get] boolA machine NaN was generated.
overflow[get] boolAn infinity was generated by overflow
overflow[get] boolAn infinity was generated by overflow
underflow[get] boolA zero was generated by underflow
underflow[get] boolA zero was generated by underflow

Example

version (InlineAsm_X86_Any)
{
    static void func() {
        int a = 10 * 10;
    }

    real a = 3.5;
    // Set all the flags to zero
    resetIeeeFlags();
    assert(!ieeeFlags.divByZero);
    // Perform a division by zero.
    a /= 0.0L;
    writeln(a); // real.infinity
    assert(ieeeFlags.divByZero);
    // Create a NaN
    a *= 0.0L;
    assert(ieeeFlags.invalid);
    assert(isNaN(a));

    // Check that calling func() has no effect on the
    // status flags.
    IeeeFlags f = ieeeFlags;
    func();
    writeln(ieeeFlags); // f
}

Authors

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

License

Boost License 1.0.