Re: [Maxima-discuss] Stair function

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

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);

Regards,

Jaime