Here's my attempt to write a guide for beginners — and some reminders for occasional users, like myself. If you find it too elementary, I also have a slightly higher-level guide to learning maxima.
Debian and most other Linux distributions have a command-line version of maxima, usually in a package with that name. If you're as un-coordinated as I am, you'll prefer this to the GUI versions like xmaxima (for the X Window System) or wxmaxima. Plain command-line maxima itself is complicated enough without having to use a mouse and navigate a nest of menus as well, so this guide will deal with just the bare-bones CLI version.
If you have never used maxima, just read on; I'll start with the most basic ideas.
If you only need a refresher on a particular topic, here are links to some important sections:
When maxima is ready for input, it presents a prompt like this:
The "%i" in the prompt tells you it's ready for input. The number that follows is part of a label that maxima assigns to your input. (These labels can be used in later input statements.) Here the label is "%i1".
Often, input statements to maxima are long, complicated expressions that need two or more lines. That means that a simple carriage return, <CR>, is not enough to mark the end of a statement. So maxima requires a special statement terminator:
; /* <semicolon><CR> prints output */
$ /* <dollar sign><CR> prints no output */
If you forget to type the statement terminator, and just hit <CR>, maxima will move the cursor down to the next line and wait patiently for more input. It ignores superfluous whitespace, so go ahead and type the terminator before pressing <CR> again.
If a statement prints output, that will be shown after a label like
where the "o" means "output" — and, again, these labels can be used in later input statements. For example:
(%i1) x; (%o1) x (%i2) y$ (%i3) %o1+%o2; (%o3) y + x (%i4)Notice that the result %o2 was actually computed; it just wasn't printed.
You'll also want to name some particular intermediate quantities, and assign values to them. I'll get to assignments shortly, below.
quit();Here, the parentheses are required because that calls a function with zero arguments. And of course the semicolon is needed to terminate the statement.
Maxima encountered a Lisp error:followed by
To enable the Lisp debugger set *debugger-hook* to nil.NO. Don't do that! The way to get back on track is to type just
:q<CR>which will get you a normal maxima input prompt.
Similarly, if you do something wrong and find yourself looking at a prompt that says
MAXIMA>>>(often with another ">" every time you hit <CR>), the way to get back to normal input is to enter just "<colon>q".
:q<CR>Once you have the regular "%i" type of prompt, you can tell it
quit();and you're back to your shell prompt.
maxima<CR>and you should see its startup message, followed by a (%i1) prompt for input.
If the shell can't find maxima, it probably hasn't been installed. Is it in one of the directories in the list printed by an
echo $PATH<CR>command? If not, you need to install it (as root).
/* This is a comment */The input parser ignores everything in a comment, including its delimiters, and replaces the whole thing with whitespace. So comments can appear anywhere in maxima input, except in the middle of a name.
print ("The result of the last calculation was",%);
(%i1) 4+5; (%o1) 9 (%i2) 4*5; (%o2) 20 (%i3) 2^3; (%o3) 8 (%i4) 2**3; (%o4) 8Notice that the regular exponentiation operator is ^, as in C; but the ** used in Fortran is also accepted.
Besides the usual operations on integers, maxima has rational numbers, such as
(%i5) 4/5; 4 (%o5) - 5that can be converted to floating-point values:
(%i6) %,numer; (%o6) 0.8 (%i7)That "(%i6)" input illustrates two more features of maxima: first, the use of "%" in an input line to mean the previous output value; and second, the addition of a comma and the condition "numer" to force decimal evaluation of any expression.
Also, notice the re-setting of the fraction in (%o5) above. That's an example of what maxima calls "two-dimensional" output. It works well for fractions, but gets messy for complicated expressions with lots of exponents and subscripts, which is why many people prefer the flavors with graphical interfaces (xmaxima and wxmaxima).
(%i13) x:5; (%o13) 5 (%i14) print("The value of x is",x); The value of x is 5 (%o14) 5Notice that the "print" function has two arguments: a text string (enclosed in double-quotes); and the variable x (which is evaluated before being printed).
? cmd <CR>at an input prompt. Notice that there is no statement terminator; you just enter the question mark, a space, and the name of the command.
Unfortunately, this prints the section of the reference manual for maxima that describes the command; but the manual is written in LISP jargon, which is a more advanced topic. Please read the references mentioned in my other page about maxima.
Actually, it turns out that this odd syntax with a question mark is just an alias for a maxima function called describe(). And there is a complication: the question mark must be the first character on the line.
A more useful form of on-line help is available through the example() function, which offers examples of the use of several topics. The problem here is that not every operation in maxima has a text file showing examples. Fortunately, the command example() (with no arguments) provides a list of all the topics for which example files exist.
There's also an apropos() function that's about as useless as the one available at a shell prompt, and for the same reason: you have to know the exact name of what you're looking for, in order to use it.
Copyright © 2020 Andrew T. Young
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