LOG10(3POSIX)

💖 LOG10(3POSIX) — POSIX Programmer's Manual 💖

okay bestie, so this is LOG10(3POSIX), straight out of the POSIX Programmer's Manual, and we're gonna get you fluent in it. 🎀

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✨ PROLOG ✨

so like, heads up: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so if you're on Linux, go check the corresponding Linux manual page for the deets on Linux behavior — or honestly the interface might not even be implemented on Linux at all. 🙈 no cap.

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🌸 NAME 🌸

log10, log10f, log10l — the base 10 logarithm function. that's it, that's the vibe. 💅

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🦋 SYNOPSIS 🦋

#include <math.h>

double log10(double x);
float log10f(float x);
long double log10l(long double x);

three icons, one family. pick your precision, slay accordingly. ✨

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💜 DESCRIPTION 💜

okay so first things first: the functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

These functions shall compute the base 10 logarithm of their argument x, log10(x). yes, the log you actually use in real life when you're counting digits. 🔥

An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. it's giving pre-flight checklist, and honestly? respect. 🫶

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👑 RETURN VALUE 👑

Upon successful completion, these functions shall return the base 10 logarithm of x. yay.

• If x is ±0, a pole error shall occur and log10(), log10f(), and log10l() shall return -HUGE_VAL, -HUGE_VALF, and -HUGE_VALL, respectively. 😭
• For finite values of x that are less than 0, or if x is -Inf, a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned.
• If x is NaN, a NaN shall be returned.
• If x is 1, +0 shall be returned. (math girlies know 💅)
• If x is +Inf, +Inf shall be returned.

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🎀 ERRORS 🎀

These functions shall fail if:

• Domain Error — The finite value of x is negative, or x is -Inf.
  • If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.
• Pole Error — The value of x is zero.
  • If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the divide-by-zero floating-point exception shall be raised.

The following sections are informative. (translation: the spicy technical part is over, now we're just chatting 🧚)

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🌈 EXAMPLES 🌈

None. bestie there are literally no examples. iconic of them honestly.

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⭐ APPLICATION USAGE ⭐

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero. they're not a package deal, but one of them has to show up. no exceptions. 💀

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🍓 RATIONALE 🍓

None. nothing to justify, the math speaks for itself. 💜

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🧚 FUTURE DIRECTIONS 🧚

None. she's not changing, she's timeless. 👑

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💅 SEE ALSO 💅

• feclearexcept()
• fetestexcept()
• isnan()
• log()
• pow()

The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.h>

iykyk — go read those next, the lore goes deep. 📚

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🌸 COPYRIGHT 🌸

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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okay that's the whole page bestie, we made it 🫶 IEEE/The Open Group — 2017 — LOG10(3POSIX) 💖✨ logging off (base 10 style) 🎀