

Show HN: Interactive maths exercises - S4M
http://magako.com/exercise/symbolic/eng

======
ColinWright
This is an exercise in extreme frustration. I know what I want it to end up
looking like, but the site seems hell-bent on making me do bizarre things that
have nothing to do with my thinking.

How is this supposed to help?

~~~
S4M
Well, you simplify the given expression by dragging one sub expression on the
other, until the remaining expression is not simplifiable anymore.

Also, while the website gives you a hint, you don't need to follow it and can
do something else instead.

Could you expand on your frustration? It would be helpful for me.

~~~
ColinWright
So I had this:

    
    
        7*8+x*6*1+x*x
    

At this point it's unclear what I should do. I dragged the 8 on top of the *
and that didn't seem to do anything. I dragged it onto the 7 and it asked what
it should be. I said "56", but it put "56.0" for some reason.

I dragged the 1 onto the x, and replaced that with "x", and now this is as
simple as it can be, really.

But no, it seems to want more. It seems it wants the "x * x" turned into x^2,
which isn't necessarily simpler. I could find no way to factor out the "x"s,
even though for some purposes that's simpler.

I can certainly find no way of converting

    
    
        x*6*9+x*x
    

into

    
    
        x(x+54)
    

even though that's the simplest form.

And if you say that you want standard form, why is

    
    
        x*54+x^2
    

the standard form, and not:

    
    
        x^2 + 54x
    

which every mathematician would prefer.

As I say, I find it an exercise in frustration, rather than enabling in any
sense. If it were clearer what was the target then it might be better, but I
don't know what it's trying to achieve.

~~~
S4M
Thank you Colin, that's a good feedback.

For me, it's not clear which is the simplest, between

    
    
        x(x+54)
    

And

    
    
        x^2+54x
    

Now, it's true that I don't take into account the orders of polynoms and don't
display the product right (for my program, 54x is just like x54). Also I need
a symbol for a product to be able to simplify expressions like:

    
    
        2*x + 3*x
    

(You would grab the first member by the product sign).

On the website I submitted I have other exercises with a free input, where you
enter directly the solution, but I think it's boring to have to enter the
whole answer in one go.

> If it were clearer what was the target then it might be better

The target should be reformulated to something like "rewrite the following
expression into a sum of monoms."

