Wrong result

[newmen]

Hello,

When I tried to use your beauty gem, I wrote this code: x = var :name => 'x' y = var :name => 'y' puts x - (y + x) / 5

And I got the next result: x-0.2*y+x

but its wrong :(

Best wishes, Gleb

[brainopia]

Indeed, I can confirm your findings. I will investigate it later, hope to get back at you soon.

Thanks for report.

[eregon]

The bug was only in the representation (#to_s), so the internal expression is correct, although not totally optimized. You can try the latest symbolic with Bundler, fetching directly from the master, or wait the next release.

[newmen]

integration_spec.rb says that failures still occur

Failures:

  1) Symbolic optimization: x-0.2*(y+x)
     Failure/Error: non_optimized.should == optimized
       expected: Symbolic(0.8*x-0.2*y)
            got: Symbolic(x-0.2*(y+x)) (using ==)
       Diff:
       @@ -1,2 +1,2 @@
       -Symbolic(0.8*x-0.2*y)
       +Symbolic(x-0.2*(y+x))
     # ./integration_spec.rb:96:in `block (4 levels) in <top (required)>'

  2) Symbolic to_s: -x**y+7
     Failure/Error: expr.to_s.should == str
       expected: "-x**y+7"
            got: "-(x**y)+7" (using ==)
     # ./integration_spec.rb:166:in `block (4 levels) in <top (required)>'

Finished in 0.01495 seconds
81 examples, 2 failures

Thus, I'm still not getting the correct result when using the expression x-(y + x)/5, i.e. is not 0.8*x-0.2*y.

[eregon]

Indeed, this expression is "not totally optimized", but both expressions are mathematically equal. So we need to work on this, but at least it's coherent now (the representation).

Do you need such simplification?

[newmen]

Your gem is perfect, because ultimately you can get an expression that contains only one time mention of a particular variable. In the case of incomplete simplify the expression - it does not. At the same time, the expression x-0.2*(y+x) can be simplified by symbolic to the correct expression. In this case you must call symbolic again, but its better not to do so. :)