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version 2.081.0

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Function std.math.truncPow2

Gives the last power of two before val. <> can be any built-in numerical type.

T truncPow2(T) (
  const T val
)
if (isIntegral!T);

T truncPow2(T) (
  const T val
)
if (isFloatingPoint!T);

Parameters

NameDescription
val any number

Returns

the last power of two before val

Example

writeln(truncPow2(3)); // 2
writeln(truncPow2(4)); // 4
writeln(truncPow2(10)); // 8
writeln(truncPow2(4000)); // 2048

writeln(truncPow2(-5)); // -4
writeln(truncPow2(-20)); // -16

writeln(truncPow2(uint.max)); // int.max + 1
writeln(truncPow2(uint.min)); // 0
writeln(truncPow2(ulong.max)); // long.max + 1
writeln(truncPow2(ulong.min)); // 0

writeln(truncPow2(int.max)); // (int.max / 2) + 1
writeln(truncPow2(int.min)); // int.min
writeln(truncPow2(long.max)); // (long.max / 2) + 1
writeln(truncPow2(long.min)); // long.min

Example

writeln(truncPow2(2.1)); // 2.0
writeln(truncPow2(7.0)); // 4.0
writeln(truncPow2(-1.9)); // -1.0
writeln(truncPow2(0.24)); // 0.125
writeln(truncPow2(-7.0)); // -4.0

writeln(truncPow2(double.infinity)); // double.infinity

Authors

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

License

Boost License 1.0.