Note the fact that decimal point taken from locale (according to SUSv2)

lib/libc/stdlib/strtod.3

@@ -69,6 +69,8 @@ or minus sign, followed by a sequence of digits.
 Leading white-space characters in the string (as defined by the
 .Xr isspace 3
 function) are skipped.
+The decimal point
+character is defined in the program's locale (category LC_NUMERIC).
 .Sh RETURN VALUES
 The
 .Fn strtod