Thank you.

I've edited this question adding a checkmark for Maple. Didn't get the badge immediately, but I'll wait for a few minutes - sometimes it takes several minutes to update scores etc.

Alec

PS Yep, several minutes later (just checked now, so can't tell exactly how much time it had taken) got it. Thanks again - Alec

Thank you.

I've edited this question adding a checkmark for Maple. Didn't get the badge immediately, but I'll wait for a few minutes - sometimes it takes several minutes to update scores etc.

Alec

PS Yep, several minutes later (just checked now, so can't tell exactly how much time it had taken) got it. Thanks again - Alec

@Christopher2222 

Yes, for all the websites - it is a lot of work. For some specific ones, with more or less stable general structure, like this forum, it is much easier, but won't work the same if the site will get updated.

Lynx and links, or Python can be used within Maple through system or ssystem commands, and text files could be read into Maple if necessary.

In general, I don't think that it is worth the time and effort for writing a general parser in Maple, because Maple is slow - for instance, XMLTools:-ParseString is very slow. I am pretty sure that there are some free ones (I mean open source) written in C, or other languages which could be compiled in a dll and used through ExternalCalling in Maple. But again - why bother (unless you are a Maplesoft developer, it is your job, and you get paid for it)? Why not to use, say lynx through ssystem?

Alec

@Christopher2222 

Yes, for all the websites - it is a lot of work. For some specific ones, with more or less stable general structure, like this forum, it is much easier, but won't work the same if the site will get updated.

Lynx and links, or Python can be used within Maple through system or ssystem commands, and text files could be read into Maple if necessary.

In general, I don't think that it is worth the time and effort for writing a general parser in Maple, because Maple is slow - for instance, XMLTools:-ParseString is very slow. I am pretty sure that there are some free ones (I mean open source) written in C, or other languages which could be compiled in a dll and used through ExternalCalling in Maple. But again - why bother (unless you are a Maplesoft developer, it is your job, and you get paid for it)? Why not to use, say lynx through ssystem?

Alec

@Oliver K 

plots:-display(plottools:-hemisphere([0,0,1],-2),
scaling=constrained, axes=boxed);

Alec

Digits:=15:
Matrix(3,(i,j)->identify(evalf([sin,cos,tan][i]([arcsin,arccos,arctan][j](2/3)/2))));

The first 2 rows can be also obtained in a uniform fashion as

Matrix(2,3,(i,j)->sqrt(combine([sin,cos][i]([arcsin,arccos,arctan][j](2/3)/2)^2)));

And the 3rd row can be calculated as

radnormal~(%[1]/~%[2],rationalized);

_______________
Alec Mihailovs, PhD

@marbovski 

That may happen if you have x assigned prior to doing that,

x:=1:
with(DifferentialGeometry):
DGsetup([x],M):
ExteriorDerivative(x^2);
Error, (in DifferentialGeometry:-ExteriorDerivative) invalid frame: DGframe_data[0][1][2]

if x is not assigned, that works,

 
restart:
with(DifferentialGeometry):
DGsetup([x],M):
ExteriorDerivative(x^2);

                                2 x dx

Alec

@marbovski 

That may happen if you have x assigned prior to doing that,

x:=1:
with(DifferentialGeometry):
DGsetup([x],M):
ExteriorDerivative(x^2);
Error, (in DifferentialGeometry:-ExteriorDerivative) invalid frame: DGframe_data[0][1][2]

if x is not assigned, that works,

 
restart:
with(DifferentialGeometry):
DGsetup([x],M):
ExteriorDerivative(x^2);

                                2 x dx

Alec

That also works without the f definition, with only `print/f` as

`print/f` := proc(x) uses Typesetting; msup(Typeset(x), mn("2")) end:

f(2);
                                 2
                                2

and with an additional f definition as

f := x -> x^2:
f(2);

                                4
'f'(2);
                                 2
                                2

No need in %f.

Alec

That also works without the f definition, with only `print/f` as

`print/f` := proc(x) uses Typesetting; msup(Typeset(x), mn("2")) end:

f(2);
                                 2
                                2

and with an additional f definition as

f := x -> x^2:
f(2);

                                4
'f'(2);
                                 2
                                2

No need in %f.

Alec

Just tried it, after putting htmstrip.exe and htmstrip.ini in /usr/local/bin (in Cygwin).

It seems as if piping doesn't work, but with saving the html file first it works as in

wget -O list1.htm http://en.wikipedia.org/wiki/List_of_HTTP_headers

htmstrip list1.htm test3.txt

The tables are rendered nicely.

The difference with links and lynx is that they produce a text file with Unix line endings, so it should be opened in something like Notepad++, and HTMSTRIP's output has Windows line endinings and can be opened in Notepad.

One restriction is that the file name should be no longer than 8 letters.

Alec

Just tried it, after putting htmstrip.exe and htmstrip.ini in /usr/local/bin (in Cygwin).

It seems as if piping doesn't work, but with saving the html file first it works as in

wget -O list1.htm http://en.wikipedia.org/wiki/List_of_HTTP_headers

htmstrip list1.htm test3.txt

The tables are rendered nicely.

The difference with links and lynx is that they produce a text file with Unix line endings, so it should be opened in something like Notepad++, and HTMSTRIP's output has Windows line endinings and can be opened in Notepad.

One restriction is that the file name should be no longer than 8 letters.

Alec

Magma is really a great package! Thank you for writing it.

@hirnyk 

Maple can plot some knots, ?algcurves[plot_knot]

Alec

@hirnyk 

y=convert(asympt(RootOf(8*x^3+y^3-6*x*y-3,y),x,2),compose,polynom,surd);

                             y = -2 x - 1

Carl DeVore said once that RealDomain should be avoided as plague. He tried to keep its existence secret from his students.

Alec

@hirnyk 

y=convert(asympt(RootOf(8*x^3+y^3-6*x*y-3,y),x,2),compose,polynom,surd);

                             y = -2 x - 1

Carl DeVore said once that RealDomain should be avoided as plague. He tried to keep its existence secret from his students.

Alec