<center><h3>Random parameters in an interactive exercise</h3></center> <p>
The use of random parameters makes your exercise much more interesting,
because it will be a different exercise
each time it is requested
.<p>
For example, the following line defines a parameter under the name of
<font color=blue><b>x1</b></font>, whose value will be a random integer
between -10 and 10 (inclusive):
<pre>
\integer{x1=random(-10..10)}
</pre>
This random parameter may then be called by the word
<b><tt class="wims_code_variable">x1</tt></b>, in the statement, the replis, the hint and the solution.
That is
, each word
<tt
class="wims_code_variable">x1
</tt
> in these texts will be replaced
by the random value of the parameter. This substitution will also take
place in the definitions of other parameters which follow that of x1.
<p>
Suppose now that you have entered
<pre>
\integer{x1=random(-10..10)}
\integer{y1=\x1+3}
</pre>
in the field of the definition of parameters, and the question
<pre>
Compute the multiplication of \x1 by \y1.
</pre>
in the statement of the exercise. Suppose that for a certain request of
the exercise, a random value <font color="red">-7</font>
is attributed to \x1. Then the following parameter \y1 will take the value
-4, and the statement of the exercise will be presented under the form <div class="wimscenter">Compute the multiplication of -7 by -4.
</div>
You may then
define a numerical reply in the name of
<tt
>The product
</tt
>,having for the good solution <tt class="wims_code_words">(\x1)*(\y1)</tt>. (Remark that here
the parentheses are necessary, because the substitution is done literarily.)
<a name="list"></a>
!if oefparm isitemof $special_parm
!changeto help/oefparm.phtml
!endif
<p>$table_header
<caption>Some other examples of parameters
!href cmd=help&special_parm=$special_parm,oefparm#list [complete list]
</caption>
$table_hdtr<th>Definition<th>Effect
$table_tr<td><tt class="wims_code_words">\real{x=random(-5..5)}</tt>
<td>\x will be a random real number<br/>between -5 and 5
$table_tr<td><tt class="wims_code_words">\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
$table_tr<td><tt class="wims_code_words">\complex{z=(1+2*i)^3}</tt>
<td>\z will be the complex number (1+2*i)^3
$table_tr<td><tt class="wims_code_words">\text{sign=random(+,-)}</tt>
<td>\sign will be a random sign: + ou -
$table_tr<td
><tt
class="wims_code_words">\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)
$table_tr<td
><tt
class="wims_code_words">\
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
$table_tr<td
><tt
class="wims_code_words">\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
$table_tr<td><tt class="wims_code_words">\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
$table_tr<td><tt class="wims_code_words">\function{h=simplify(x^5*y^3*x^2/y)}</tt>
<td>Simplified expression: x<sup>7</sup>y<sup>2</sup>
$table_tr<td
><tt
class="wims_code_words">\
function{g
=diff
(sin(x
)+cos(y
),x
)}</tt
> <td
>\g will the the derivative of
sin(x
)+cos(y
) with respect to x
$table_tr<td><tt class="wims_code_words">\function{F=int(x^2+3*x+1,x)}</tt>
<td>\F will an antiderivative of x^2+3*x+1,<br/>
the
constant term being not garanteed to be always the same
!!$table_tr<td><tt class="wims_code_words">\function{F=int(t^2+3*t+1,t=1..x)}
!! <td>\F will the antiderivative of x^2+3*x+1 with g(1)=0
$table_tr<td><tt class="wims_code_words">\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
$table_tr<td><tt class="wims_code_words">\text{f=htmlmath(2*x^2+3*x)}</tt>
<td>\f will be rendered in html as: 2x<sup>2</sup>+3x
$table_tr<td><tt class="wims_code_words">\text{f=texmath(2*x^2+3*x)}</tt>
<td>\f will be the TeX source for the expression.
$table_tr<td><tt class="wims_code_words">\integer{n=items(a,b,c,d,e,f)}</tt>
<td
>\n will be the number of items
(here it is
6) in the
list {a,b,c,d,e,f}
$table_tr<td><tt class="wims_code_words">\text{i=item(3,a,b,c,d,e,f)}</tt>
<td
>\i will be the item number
3 of the
list {a,b,c,d,e,f} (hence c).
$table_tr<td
><tt
class="wims_code_words">\text
{s
=shuffle(6)}</tt
> <td
>\s will be the
list of
6 integers
1,2,...,6, in random order
. $table_tr<td
><tt
class="wims_code_words">\text
{s
=shuffle(a
,b
,c
,d
,e
)}</tt
> <td>\s will be the letters {a,b,c,d,e} in random order.
$table_tr<td><tt class="wims_code_words">\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.
$table_tr<td><tt class="wims_code_words">\text{t=asis(How do you do? item(1,2,3))}</tt>
<td>The string as it is, with no transformation nor conditionality.
$table_end <p>
Conditional parameters: You may write
<pre>
\text{ttt=_condition?_def1}
\text{ttt=_condition?_def1:_def2}
</pre>
<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).
!href target
=wims_mhelp cmd
=help
&special_parm
=if List of conditions
<p>
The relative positionning of the definition and the statement is important:
if a variable is
defined AFTER the statement
, the evaluation of the variable
will take place only AFTER the user has replied to the question. In this
case, the definition may involve user replies, via <tt class="wims_code_variable">\reply1</tt>,
<tt class="wims_code_variable">\reply2</tt>, etc. And the variable can be used in testing
conditions or feedbacks.