text: #include "libc/math/libm.h"
  
  /* asinh(x) = sign(x)*log(|x|+sqrt(x*x+1)) ~= x - x^3/6 + o(x^5) */
  float asinhf(float x)
  {
  	union {float f; uint32_t i;} u = {.f = x};
  	uint32_t i = u.i & 0x7fffffff;
  	unsigned s = u.i >> 31;
  
  	/* |x| */
  	u.i = i;
  	x = u.f;
  
  	if (i >= 0x3f800000 + (12<<23)) {
  		/* |x| >= 0x1p12 or inf or nan */
  		x = logf(x) + 0.693147180559945309417232121458176568f;
  	} else if (i >= 0x3f800000 + (1<<23)) {
  		/* |x| >= 2 */
  		x = logf(2*x + 1/(sqrtf(x*x+1)+x));
  	} else if (i >= 0x3f800000 - (12<<23)) {
  		/* |x| >= 0x1p-12, up to 1.6ulp error in [0.125,0.5] */
  		x = log1pf(x + x*x/(sqrtf(x*x+1)+1));
  	} else {
  		/* |x| < 0x1p-12, raise inexact if x!=0 */
  		FORCE_EVAL(x + 0x1p120f);
  	}
  	return s ? -x : x;
  }
  