Hi Wolfgang,

Thanks for your attention, but the problem with your solution is that each instance of \RandomFunctionName changes the name chosen, but I need something wihich remains the same name within a given situation (say each problem) but changes from problem to problem. 

For instance when using your solution with the source code

	Give an example of a function $\RandomFunctionName : {\Bbb R} \longrightarrow {\Bbb R}$ which has a 
	derivative only at the origin, and such that $\RandomFunctionName(0) = 1$.
gives:
	Give an example of a function 𝐺 : R ⟶ R which has a derivative only at the origin, and such that 𝑊(0) = 1. 

while what I need is 
	Give an example of a function 𝐺 : R ⟶ R which has a derivative only at the origin, and such that G(0) = 1. 

(The macro I sent earlier does this, but unfortunately it cannot use the solution you sent).
Is there a solution ?

Best regards: OK

> On 18 Apr 2015, at 19:23, Wolfgang Schuster <schuster.wolfgang@gmail.com> wrote:
> 
> 
>> Am 18.04.2015 um 18:55 schrieb Otared Kavian <otared@gmail.com>:
>> 
>> Hi everyone,
>> 
>> In the example below I define a macro which chooses at random a name from a list of names. But I wonder whether this can be done in a more clever way without using a numerical macro created with math.random in Lua. The shortcoming of the macro below is that before hand I must know the nomber of elements in the list of names (for instance 5 in the example below), while it may happen that I need to create as many as random names that there are elements in the list, but sometimes I don’t know what is this number.
>> 
>> Thanks for any insight and help.
>> Best regards: OK
>> %%%% begin random-names.tex
>> \setuprandomize[2015] % set a seed
>> 
>> \starttext
>> 
>> \startluacode
>> 	Name = {'F', 'G', 'u', 'v', 'W'}
>> \stopluacode
>> 
>> \define[3]\RandomName{%
>> 	\setevalue{Named#1}{\ctxlua{tex.print(math.random(#2,#3))}}}
>> \define\RandomFunctionName{\ctxlua{tex.print(Name[\NamedFunctionNumber])}}
>> 
>> \dorecurse{10}{\RandomName{FunctionNumber}{1}{5}%
>> Give an example of a function $\RandomFunctionName : {\Bbb R} \longrightarrow {\Bbb R}$ which has a derivative only at the origin, and such that $\RandomFunctionName(0) = 1$.\par \hairline\par}
>> 
>> \stoptext
>> %%%% begin random-names.tex
> 
> You can access the size of your Name table with #Name but have to replace # with \letterhash when you use it in a TeX command because # is already taken for the TeX arguments.
> 
> \starttext
> 
> \startluacode
> 	Name = {'F', 'G', 'u', 'v', 'W'}
> \stopluacode
> 
> \define\RandomFunctionName
>  {\startlua
>   local listsize    = \letterhash Name ;
>   local randomvalue = math.random(1,listsize) ;
>   context(Name[randomvalue])
>   \stoplua}
> 
> \dorecurse{10}{Give an example of a function $\RandomFunctionName : {\Bbb R} \longrightarrow {\Bbb R}$ which has a derivative only at the origin, and such that $\RandomFunctionName(0) = 1$.\par \hairline\par}
> 
> \stoptext
> 
> Wolfgang
> 
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