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Function std.math.exponential.expm1

Calculates the value of the natural logarithm base (e) raised to the power of x, minus 1.

real expm1 (
  real x
) pure nothrow @nogc @trusted;

double expm1 (
  double x
) pure nothrow @nogc @safe;

float expm1 (
  float x
) pure nothrow @nogc @safe;

For very small x, expm1(x) is more accurate than exp(x)-1.

Special Values
x ex-1
±0.0 ±0.0
+∞ +∞
-∞ -1.0


import std.math.traits : isIdentical;
import std.math.operations : feqrel;

assert(isIdentical(expm1(0.0), 0.0));
assert(expm1(1.0).feqrel(1.71828) > 16);
assert(expm1(2.0).feqrel(6.3890) > 16);


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


Boost License 1.0.