<p>In all of my classes when we say Log we are refering to logarithm based e. But I hear engineering classes when they use log they are refering to log base 10. Is this true?</p>
<p>log is base 10. ln (pronounced lawn) is base e. This is standard, regardless of your major, which school you go to, and even which country you live in.</p>
<p>I go to school in the U.S.</p>
<p>UCDavis.</p>
<p>Most mathematicians and Statiticians refer to log as log base e, not base 10.</p>
<p>in every school I have been to (around the coutnry) base 10 is "log" while base e is "natural log"</p>
<p>hence in calculators you will find two keys "log" and "ln"</p>
<p>In MatLab, Maple, and Mathmatica Log = Log base e.</p>
<p>I have books written by professors at MIT, Stanford, Cal, ect and all of them refer to log as base e.</p>
<p>They're noobs :P ln is there for a reason.</p>
<p>
[quote]
They're noobs :P ln is there for a reason.
[/quote]
</p>
<p>Odd ln doesn't seem to be there on my MatLab program.</p>
<p>Call it what you want as long as you write ln when you mean log base e and log (no subscript) when you mean log base 10</p>
<p>
[quote]
Call it what you want as long as you write ln when you mean log base e and log (no subscript) when you mean log base 10
[/quote]
</p>
<p>No thank you I will continue to write it how most people in my field write it with log being log base e.</p>
<p>I have heard "log" refer to logarithms of base 10 and base e in my Calculus courses, as well as base 2 in my Computer Science courses (especially for algorithm complexity). :rolleyes:</p>
<p>log 10
ln e</p>
<p>I have nothing of value to add to this discussion.</p>
<p>Alright let's settle this once and for all.</p>
<p>vote: does log mean base 10 or base e.
The score so far:</p>
<p>log(x) (with no base specified) is of which base:
---base 10: 4
---base e: 1</p>
<p>From wikipedia:</p>
<p>The notation "ln(x)" invariably means loge(x), i.e., the natural logarithm of x, but the implied base for "log(x)" varies by discipline:</p>
<pre><code>* Mathematicians generally understand both "ln(x)" and "log(x)" to mean loge(x) and write "log10(x)" when the base-10 logarithm of x is intended. Sometimes the term "ld(x)" is used for the base-10 logarithm of x and "lg(x)" for the base-2 logarithm of x.
Engineers, biologists, and some others write only "ln(x)" or "loge(x)" when they mean the natural logarithm of x, and take "log(x)" to mean log10(x) or, sometimes in the context of computing, log2(x).
On most calculators, the LOG button is log10(x) and LN is loge(x).
In most commonly used computer programming languages, including C, C++, Java, Fortran, and BASIC, the "log" or "LOG" function returns the natural logarithm. The base-10 function, if it is available, is generally "log10."
Sometimes Log(x) (capital L) is used to mean log10(x), by those people who use log(x) with a lowercase l to mean loge(x).
The notation Log(x) is also used by mathematicians to denote the principal branch of the (natural) logarithm function.
Also frequently used is the notation blog(x) instead of logb(x).
</code></pre>
<p>As recently as 1984, Paul Halmos in his "automathography" I Want to Be a Mathematician heaped contempt on what he considered the childish "ln" notation, which he said no mathematician had ever used. (The notation was in fact invented in 1893 by Irving Stringham, professor of mathematics at Berkeley.) As of 2005, some mathematicians have adopted the "ln" notation, but most use "log".</p>
<p>In computer science, the base 2 logarithm is sometimes written as lg(x) to avoid confusion. This usage was suggested by Edward Reingold and popularized by Donald Knuth. However, in Russian literature, the notation lg(x) is generally used for the base 10 logarithm, so even this usage is not without its perils.[1].</p>
<p>You know what, it really doesn't matter. As long as all the parties involved understand the context in which log is used, then it's fine.</p>
<p>I will personally stick with log for 10 when no base is specified and ln for e.</p>
<p>Yeah, except that the way logarithms are bandied about with 'understood' unspoken bases of who-knows-what, <em>nobody</em> understands the context in which log is used.</p>
<p>I always ask, if I'm referring to a source whose conventions I'm unfamiliar with, or I look at example problems and crunch a few numbers to confirm what base they're using... and honestly, it's a toss-up as to what the base ends up being, e or 10.</p>
<p>So... good luck with that!</p>
<p>to me, i always consider log (with base unspecified) to mean log base e (ln), except in relation to computer science and digital systems, where it is invariably log base 2. the base, e vs. 2, is usually clear from the context.</p>
<p>Outside of some particulars (pH scale, decibels, richter, etc) absolutely no one uses log base 10 in engineering.</p>
<p>I know someone who has thier Ph.D in Aerospace Engineering from Stanford, and he tells me they use log to refer to log based e. So perhaps it depends on which engineering field too.</p>
<p>It depends on the field. In math, base 10 logarithms aren't nearly as important as base e logarithms, so "log" implies base e. In other disciplines, base 10 may be more important. In high school math, "log" is almost always used to mean base 10.</p>
<p>Bottom line is, there's no best answer, so it's pointless arguing about.</p>
<p>e and ln. </p>
<p>ln = "natural log"</p>
<p>log = ambiguous. can be any base. in class, they'll usually specify explicitly.</p>