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2. Using Array Syntax
Most Yorick statements look like algebraic formulas. A variable name is
a string like Var_1  upper or lower case characters (case
matters), digits, or underscores in any combination except that the
first character may not be a digit. Expressions consist of the usual
arithmetic operations +  * /, with parentheses to indicate the
order of operations (when that order is different than or unclear from
the ordinary rules of precedence in algebra). Elementary mathematical
functions such as exp(x), cos(x), or atan(x) look just
like that.
Usually, a Yorick variable is a parametric representation of a
mathematical function. The variable is an array of numbers which are
values of the function at a number of points; few points to represent
the function coarsely, more for an accurate rendition. The parameters
of the function are the indices into the array, which rarely make an
explicit appearance in Yorick programs. Thus,
 theta = span(0.0, 2*pi, 100)

defines a variable theta consisting of 100 evenly spaced values
starting with 0.0 and ending with 2*pi.
Now that theta has been defined as a list of 100 numbers, any
function of theta has a concrete representation as a list of 100
numbers  namely the values of the function at the 100 particular
values of theta. Hence, variables x and y
representing coordinates of the unit circle are defined with:
 x = cos(theta); y = sin(theta)

Here, cos and sin are builtin Yorick functions. Like most
Yorick functions, they operate on an entire array of numbers, returning
an array of like shape. Hence both x and y are now lists of
100 numbers  the cosines and sines of the 100 numbers
theta.
The semicolon marks the end of a Yorick statement, allowing several
statements to share a single line. The end of a line (i.e. a newline)
can also mark the end of a Yorick statement. However, if any
parentheses are open, or if a binary operator or a comma is the last
token on the line, then the newline is treated like a space or a tab
character and does not terminate the Yorick statement.
If a line ends with backslash, the following newline will never
terminate the Yorick statement. (That is, backslash is the continuation
character in Yorick.) I recommend that you never use a backslash  end
the line to be continued with a binary operator, or leave the comma
separating subroutine arguments at the end of the line, or split a
parenthetic expression across the line, and it will be continued
automatically.
