On Apr 5, 9:06 am, Golam Mortuza Hossain <gmhoss...@gmail.com> wrote:
> Hi,
>
> On Sat, Apr 4, 2009 at 4:06 PM, Robert Bradshaw
>
> <rober...@math.washington.edu> wrote:
>
> > On Apr 3, 2009, at 7:16 PM, Nick Alexander wrote:
>
> >>> (1) \int dx f(x)
> >>> (2) \int f(x) dx
>
> >> I prefer (2).
>
> > I've actually never seen (1) used; (2) seems much more natural. The
> > "\int dx \int dy f" is strange as the "dx dy" is often best viewed as
> > single differential.
>
> Thanks Nick, Robert! OK, then we settle on (2) for integral.
The only people I know who use the other ordering are physicists with
14-deep integrals, where associating the variable and the limits is
MUCH easier with version 1. There may be other people, too.
>
> The remaining issue is now to settle the conventions for derivative.
> Currently, maxima uses "\\partial" symbol even for functions
> of single variable.
This does not seem to be true.
I just ran Maxima on 'diff(f(x),x) and I got this:
{d}\over{d\,x}}\,f\left(x\right)
So if it uses \partial, it is because Sage is messing it up.
> I think it would be better if we follow the
> arguments ofhttp://trac.sagemath.org/sage_trac/ticket/4202
> for derivative of function with single variable. So here are the situations
>
> (1) diff( f(x), x) =>
> --------------------
> (a) Current scheme via Maxima:
> {{{\it \partial}}\over{{\it \partial}\,x}}\,f\left(x\right)
>
> (b) Proposed:
> \frac{d f\left(x\right)}{d x}
>
> (2) diff( f(x, y), x) =>
> --------------------
> (a) Current scheme via Maxima:
> {{{\it \partial}}\over{{\it \partial}\,x}}\,f\left(x, y\right)
>
> (b) Proposed:
> \frac{\partial f\left(x, y\right)}{\partial x}
I don't know what problem is being solved by this change, but the
notation for derivatives that you are proposing is inadequate for the
breadth of expressions possible. This has been well known in the CAS
community for decades.
For example, consider diff(f(x^2,y(x)^2), x), which could be
expanded to 2*x*f^(1)(f(x^2,y(x)^2)+ 2*y^(1)*y(x)*f^(2)(x^2,y(x)^2)
or some such. So you need a notation for the derivative of f or y
with respect to its first [positional] argument.
etc.
see
Differentiation of unknown functions in MACSYMA
Source ACM SIGSAM Bulletin archive
Volume 19 , Issue 2 (May 1985) table of contents
Pages: 19 - 24
Year of Publication: 1985
ISSN:0163-5824
Author
Jeffrey P. Golden
>
> We follow similar scheme for higher derivatives.
>
> Once this convention is settled, I will be ready to submit
> the final patch including doc-tests.
>
> Cheers,
> Golam
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