<p> 
You can define variables in your documents, and call them later (within a
same page), thus making your document more dynamic.

For example, the following line defines a variable under the name of
<font color="blue"><b>x1</b></font>, whose value will be a random integer
between -10 and 10 (inclusive):
<pre>
\\def{integer x1=random(-10..10)}
</pre>
This random parameter may then be called by the word
<b><tt>\\x1</tt></b>, in the rest of the block defining it.
That is, each word <tt>\\x1</tt> will be replace by the random value
of the variable. This substitution will also take effect within definitions
of other variables following it.

\def{integer x1=random(10..50)}
\def{integer y1=random(10..50)}
\def{integer xy=\x1*\y1}
For example, in this page we have defined
<pre>
\\def{integer x1=random(10..50)}
\\def{integer y1=random(10..50)}
\\def{integer xy=\\x1*\\y1}
</pre>
Consequently, the text <tt>\\x1*\\y1=\\xy</tt> gives
\x1*\y1=\xy. You may \reload{renew the page} to see the values change.
<p><center>Some other examples of variables
\help{module=adm/doc.en&job=help&help_subject=oefparm}
{[Complete list]}
<table border=2 bgcolor="bisque">
<tr><th>Definition<th>Effect</th></tr>
<tr><td><tt>\\def{real x=random(-5..5)}</tt>
    <td>\\x will be a random real number<br>between -5 and 5</td></tr>
<tr><td><tt>\\def{real a=random(-5,-3,0.3,4)}</tt>
    <td>\\a will be a real number taken randomly<br>among -5,-3,0.3 and 4
    </td></tr>
<tr><td><tt>\\def{complex z=(1+2*i)^3}</tt>
    <td>\\z will be the complex number z=\((1+2*i)^3)
    </td></tr>
<tr><td><tt>\\def{text sign=random(+,-)}</tt>
    <td>\\sign will be a random sign: + ou -
    </td></tr>
<tr><td><tt>\\def{integer n=3*exp(\\a)}</tt>
    <td>\\n will be the closest integer to 3*e<sup>\\a</sup><br>(it
    depends on the value of \\a)
    </td></tr>
<tr><td><tt>\\def{function f=random<br>(x^2+1,sin(x),log(x))}</tt>
    <td>\\f will be a random function: either \(x^2+1),<br>or sin(x), or log(x)
    </td></tr>
<tr><td><tt>\\def{text s=shuffle(6)}</tt>
    <td>\s will be a list of 6 integers 1,2,...,6, in random order.
    </td></tr>
<tr><td><tt>\\def{text s=shuffle(a,b,c,d,e)}</tt>
    <td>\s will be the letters {a,b,c,d,e} in random order.</td></tr>
<tr><td><tt>\\def{real a=evalue(x^2+sin(y),x=3,y=4)}</tt>
    <td>Evaluation of the function \(x^2+sin(y)),<br>
    for x=3, y=4</td></tr>
<tr><td><tt>\\def{real r=solve(x^3-3*x+1,x=0..1)}</tt>
    <td>\\r will the the simple root of \(x^3-3x+1) between 0 and 1</td></tr>
<tr><td><tt>\\def{function h=simplify(x^5*y^3*x^2/y)}</tt>
    <td>Simplified expression: \(x^7*y^2)</td></tr>
<tr><td><tt>\\def{function g=diff(sin(x)+cos(y),x)}</tt>
    <td>\\g will the the derivative of sin(x)+cos(y) with respect to x</td></tr>
<tr><td><tt>\\def{function F=int(x^2+3*x+1,x)}</tt>
    <td>\\F will an antiderivative of \(x^2+3*x+1),<br>
     the constant term being not garanteed to be always the same
\comment{<tr><td><tt>\\def{function F=int(t^2+3*t+1,t=1..x)}</tt>
    <td>\\F will the antiderivative of \(x^2+3*x+1) such that F(1)=0}</td></tr>
<tr><td><tt>\\def{real a=int(t^2+3*t+1,t=0..1)}</tt>
    <td>\a will the numerical integral of \(x^2+3*x+1), from 0 to 1</td></tr>
<tr><td><tt>\\def{text f=htmlmath(2*x^2+3*x)}</tt>
    <td>\\f will be rendered in html as: \(2x^2+3x)</td></tr>
<tr><td><tt>\\def{text f=texmath(2*x^2+3*x)}</tt>
    <td>\\f will be the TeX source for the expression.</td></tr>
<tr><td><tt>\\def{matrix m=1,2,3<br>4,5,6<br>7,8,9}</tt>
    <td>\\m will be the matrix of 3 rows and 3 columns.
</td></tr>
</table></center><p> 
Conditional parameters: You may write<p>
<tt>\\def{text ttt=_condition?_def1}</tt> or <br>
<tt>\\def{text ttt=_condition?_def1:_def2}</tt>
<p>
In this case, <tt>\\ttt</tt> will be set to <tt>_def1</tt> if
<tt>_condition</tt> is true, or to <tt>_def2</tt> otherwise (in the second
syntax).
\help{module=adm/doc&cmd=new&job=help&help_subject=if}{List of conditions}

Finally, note that inserted blocks via
\link{fold}{<tt>\fold</tt>} or \link{embed}{<tt>\embed</tt>} inherit the
definitions of variables before insertion.