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Subject: sqrtl behavior inconsistent with sqrt and sqrtf
Date: Tue, 27 Oct 2020 07:17:01 -0400
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Content-Type: text/plain

Compiling and running the attached program with the command line below
produces the output below:

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Content-Type: text/plain
Content-Disposition: inline; filename=test_sqrt.c
Content-Description: Test program for sqrtl, sqrt, and sqrtf

#include <math.h>
#include <stdio.h>

int main() {
  long double a, b;
  double c, d;
  float f, g;
  a = (long double) -INFINITY;
  c = (double) -INFINITY;
  f = (float) -INFINITY;
  b = sqrtl(a);
  d = sqrt(c);
  g = sqrtf(f);
  printf("Long double: %4Lf %4Lf\n", a, b);
  printf("Double:      %4lf %4lf\n", c, d);
  printf("Float:       %4f %4f\n", f, g);
  return 0;
}

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Content-Type: text/plain


$ gcc -O0 -Og test_sqrt.c -o test_sqrt && ./test_sqrt
Long double: -inf -inf
Double:      -inf -nan
Float:       -inf -nan

I suspect the behavior for long double should be the same as for double
and float (sqrt(-inf) = nan), but I'm not sure where to change that.
I'm running a snapshot of Cygwin 3.2.0, if that's important.

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