Display problem in the plot window

[David Boucher]

I wanted to plot the function x/abs[x]. Because of a bug in the convertions between integers and reals I couldn't. But now, if you work with the last CVS version of numexp-core, you can.

But, the legend shows something strange that mixes the two notations : abs(x) and |x|.

I don't see how to join an image of what I get... but you can ask me... :-)

[David Boucher (bouda1)]

So here is the picture I get.

[Gustavo Carneiro (gjc)]

This is a numexp-core problem:

::> eval[mathml[x/abs[x]]]
ans = "<mrow><mfrac><mi>x</mi><mrow><mi>abs</mi><mo>⁡</mo><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mfrac></mrow>"

[Alberto Simões (ambs)]

This is not a numexp-core bug but a mathml rendering bug. The problem is that the two parts of the parenthesis are being drawn too closely on the small abs[x], thus producing that effect.

Although I am changing the mathml notation for abs I think this will happen for others functions, like sine or cosine.

Gustavo, please change this bug to gNumExp again (can't find the option anywhere).

Thanks
Alberto

[Gustavo Carneiro (gjc)]

The expression 'abs[x]' is being converted to the MathML:

<mrow><mi>abs</mi><mo>⁡</mo><mo>(</mo><mi>x</mi><mo>)</mo></mrow>

(where '⁡' is &ApplyFunction;)
This is not correct, should be
<mrow><mi>abs</mi><mo>&ApplyFunction;</mo><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mrow>

That is, ( and ) should be start and end of an mrow of its own, for purposes of correct vertical stretching.

So there is a small bug in numexp-core at least.

Besides that, I simply cannot reproduce David's problem here. I only see abs(x) in the rendered MathML, I don't see (|x|).

[Alberto Simões (ambs)]

Fixed in numexp-core

Gustavo Carneiro wrote:
> The expression 'abs[x]' is being converted to the MathML:
>
> <mrow><mi>abs</mi><mo>⁡</mo><mo>(</mo><mi>x</mi><mo>)</mo></mrow>
>
> (where '⁡' is &ApplyFunction;)
> This is not correct, should be
> <mrow><mi>abs</mi><mo>&ApplyFunction;</mo><mrow><mo>(</mo><mi>x</mi><mo>)</mo></mrow></mrow>
>
> That is, ( and ) should be start and end of an mrow of its own, for
> purposes of correct vertical stretching.
>
> So there is a small bug in numexp-core at least.
>
> Besides that, I simply cannot reproduce David's problem here. I only
> see abs(x) in the rendered MathML, I don't see (|x|).
>

--
Alberto Simões - Departamento de Informática - Universidade do Minho
                  Campus de Gualtar - 4710-057 Braga - Portugal

"Beware of bugs in the above code;
  I have only proved it correct, not tried it."
                                    --- Donald Knuth

[Gustavo Carneiro (gjc)]

Fixed in numexp-core and gnumexp; they both had their share of bugs :P