Re: [Maxima-discuss] Stair function

[Jaime V. <vi...@fe...>]

On 06/04/24 19:30, Jaime Villate via Maxima-discuss wrote:
>
>
> On 06/04/24 19:20, Robert Dodier wrote:
>> I traced E and g and I think what's happening is that 'if x = b then
>> ... ' fails if x is a float and b is an integer, but x is equal to
>> float(b). Then the loop runs all the way through and eventually yields
>> 'done'. That nonnumeric value causes plot2d to complain.
>>
>> There have been various changes to plot2d over the last couple of
>> years, and it seems likely OP is running a version which refuses to
>> plot if even one value is nonnumeric. The current version just filters
>> out nonnumeric values, which is, I think, as it should be (and has
>> been at times in the past).
>
> That makes sense.
>
> In any case, the "staircase" that Pierre wants to plot is definitely 
> not a function but a polygonal line, so I suggest to use the following 
> approach (which is what staircase does in my dynamics package):
>
> stair(f,n,a,b):=block
>    ([r:[[a,f(a)]], s:(b-a)/n, y: f(a)],
>     for x:a+s thru b step s do
>       (r: append(r, [[x, y], [x, f(x)]]), y: f(x)),
>     r)$
> f(x):=1/(1+x)$
> plot2d([f,[discrete, stair(1/(1+x),10,0,1)]], [x,0,1], nolegend);

That's correct but I mean to say:

plot2d ([f, [discrete, stair (f, 10, 0, 1)]], [x, 0, 1], nolegend);

and if Pierre is using and old version of Maxima, he will probably need 
[legend,false] instead of nolegend.

Jaime