Mathematica usually pays no attention to whether variables like x stand for real or complex numbers. Sometimes, however, you may want to make transformations which are ...

In most cases, you want the head f of a Mathematica expression like f[x] to be a single symbol. There are, however, some important applications of heads that are not symbols. ...

Finding elements that match a pattern. This gives the elements of the list which match the pattern x^_. Here is the total number of elements which match the pattern.

In doing many kinds of calculations, you need to evaluate expressions when variables take on particular values. In many cases, you can do this simply by applying ...

Finding the structure of polynomials written in expanded form. Here is a polynomial in two variables. This is the polynomial in expanded form.

Specifying formats for text in graphics. Here is a plot with default settings for all formats. Here is the same plot, but now using a 12-point bold font.

Here is one way to enter a particular expression. Here is another way to enter the same expression. With a notebook front end, you can also enter the expression directly in ...

A Frobenius equation is an equation of the form where a_1, …, a_n are positive integers, m is an integer, and the coordinates x_1, …, x_n of solutions are required to be ...

When you make a function definition using :=, the value of the function is recomputed every time you ask for it. In some kinds of calculations, you may end up asking for the ...

Unless f is a flat function, a pattern like f[x_,y_] stands only for instances of the function with exactly two arguments. Sometimes you need to set up patterns that can ...