# [Bug 268421] ATAN2(3) manpage contains UTF8 character codes

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*From:***Sat, 17 Dec 2022 00:46:05 UTC**

*Date:*https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=268421 Bug ID: 268421 Summary: ATAN2(3) manpage contains UTF8 character codes Product: Documentation Version: Latest Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: Manual Pages Assignee: bugs@FreeBSD.org Reporter: dclarke@blastwave.org CC: doc@FreeBSD.org Looking at the manpage for ATAN2(3) where I see the strange usage of some UTF8 characters where a trivial asterisk '*' would be fine. This page does not render on my XTerm with a whole collection of fonts available. $ uname -apKU FreeBSD callisto 13.1-RELEASE-p3 FreeBSD 13.1-RELEASE-p3 GENERIC amd64 amd64 1301000 1301000 $ man atan2 | grep 'satisfy' | hdump -Ax -t x1 -v 0: 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 10: 73 61 74 69 73 66 79 20 78 20 3d 20 72 e2 88 97 20: 63 6f 73 20 74 68 65 74 61 20 61 6e 64 20 79 20 30: 3d 20 72 e2 88 97 73 69 6e 20 74 68 65 74 61 2e 40: 20 20 54 68 65 73 65 20 65 71 75 61 74 69 6f 6e 50: 73 0a 52: $ There we see the strange UTF-8 char byte sequence "e2 88 97". On NetBSD 9.3 I see : NOTES The function atan2() defines "if x > 0," atan2(0, 0) = 0 on a VAX despite that previously atan2(0, 0) may have generated an error message. The reasons for assigning a value to atan2(0, 0) are these: 1. Programs that test arguments to avoid computing atan2(0, 0) must be indifferent to its value. Programs that require it to be invalid are vulnerable to diverse reactions to that invalidity on diverse computer systems. 2. The atan2() function is used mostly to convert from rectangular (x,y) to polar (r,theta) coordinates that must satisfy x = r*cos theta and y = r*sin theta. These equations are satisfied when (x=0,y=0) is mapped to (r=0,theta=0) on a VAX. In general, conversions to polar coordinates should be computed thus: r := hypot(x,y); ... := sqrt(x*x+y*y) theta := atan2(y,x). 3. The foregoing formulas need not be altered to cope in a reasonable way with signed zeros and infinities on a machine that conforms to IEEE 754; the versions of hypot(3) and atan2() provided for such a machine are designed to handle all cases. That is why atan2(+-0, -0) = +-pi for instance. In general the formulas above are equivalent to these: r := sqrt(x*x+y*y); if r = 0 then x := copysign(1,x); Those are trivial asterisk chars 0x2A ASCII and they work everywhere. -- Dennis Clarke RISC-V/SPARC/PPC/ARM/CISC UNIX and Linux spoken GreyBeard and suspenders optional -- You are receiving this mail because: You are the assignee for the bug.