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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

pragma(inline, false) static void blockopt(ref real x) {}
resetIeeeFlags();
real a = 3.5;
blockopt(a); // avoid constant propagation by the optimizer

a /= 0.0L;
writeln(a); // real.infinity
assert(ieeeFlags.divByZero);
blockopt(a); // avoid constant propagation by the optimizer

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

Function ieeeFlags

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

Returns

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

Example

pragma(inline, false) static void blockopt(ref real x) {}
resetIeeeFlags();
real a = 3.5;
blockopt(a); // avoid constant propagation by the optimizer

a /= 0.0L;
writeln(a); // real.infinity
assert(ieeeFlags.divByZero);
blockopt(a); // avoid constant propagation by the optimizer

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

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

Example

static void func() {
    int a = 10 * 10;
}
pragma(inline, false) static void blockopt(ref real x) {}
real a = 3.5;
// Set all the flags to zero
resetIeeeFlags();
assert(!ieeeFlags.divByZero);
blockopt(a); // avoid constant propagation by the optimizer
// Perform a division by zero.
a /= 0.0L;
writeln(a); // real.infinity
assert(ieeeFlags.divByZero);
blockopt(a); // avoid constant propagation by the optimizer
// 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

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

Example

static void func() {
    int a = 10 * 10;
}
pragma(inline, false) static void blockopt(ref real x) {}
real a = 3.5;
// Set all the flags to zero
resetIeeeFlags();
assert(!ieeeFlags.divByZero);
blockopt(a); // avoid constant propagation by the optimizer
// Perform a division by zero.
a /= 0.0L;
writeln(a); // real.infinity
assert(ieeeFlags.divByZero);
blockopt(a); // avoid constant propagation by the optimizer
// 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.