wxMaxima doesn't give a numerical answer - even when using float()

Question

I tried setting up a simple function in wxMaxima - but find that the answer is symbolic. I've tried using float() in conjunction with the function that I've created, but float() doesn't fully convert the symbolic answer to a single number.

Is there any way to get a numeric answer from the following?

Below is how I set up the function in wxMaxima. It is hard to see since this message isn't graphical - but the issue I have is that the exponential never gets evaluated for some reason. Why?

EDIT: I've added a screen capture (easier to read).

enter image description here

side note: I think part of the information below is in the LaTex Format (not sure) - I'm referring to: (\ensuremath{\alpha})

(%i3)   R1:500;
500(R1)
(%i4)   R2:540;
540(R2)
(%i5)   C:1E−6;
1.010−6(C)
(%i6)   RC:R1·R2;
270000(RC)
(%i7)   α:R2/(R1+R2);
2752(\ensuremath{\alpha})
(%i8)   Vs:1;
1(Vs)
-->     
Vo(t):=Vsα(1−e−tRC)(%o9)
(%i10)  Vo(200E−6);
27(1−1e7.40740740740740810−10)52(%o10)
(%i14)  %o10, number;
27(1−1e7.40740740740740810−10)52(%o14)
(%i15)  float(%o14);
0.5192307692307693(1.0−1.0e7.40740740740740810−10)(%o15)

Answer 1

Hmm, I can't confirm the behavior you are seeing. Here's what I get. I am working with the Maxima console interface instead of wxMaxima, I don't know if that makes a difference.

(%i2) R1:500;
(%o2)                          500
(%i3) R2:540;
(%o3)                          540
(%i4) C:1E-6;
(%o4)                        1.0E-6
(%i5) RC:R1*R2;
(%o5)                        270000
(%i6) α:R2/(R1+R2);
                               27
(%o6)                          --
                               52
(%i7) Vs:1;
(%o7)                           1

(%i10) Vo(t) := Vs * α * (1 - exp(-t/(RC)));
                                         - t
(%o10)            Vo(t) := Vs α (1 - exp(---))
                                         RC
(%i11) Vo(200E-6);
(%o11)                3.846153587924088E-10

What do you get for exp(7.4e-10) ? I get 1.00000000074.

What is the output of wxbuild_info(); ?

Answer 2

I think you have to use %e (with %) for the exponential.