Why is it possible for http://www.mapleprimes.com/users/abraham to continue posting spam ? It is incredibly irritating for me, and I presume it must be for other bona fide users. Why can't the account be disabled, made inactive, or whatever is necessary to stop this ridiculous activity ?

In this post I will describe a little about the OU course MS325: Computer Algebra, Chaos and Simulations, which I took last year.

MS325 is a level 3 OU applied mathematics course, which means, roughly that it is pitched at the level of a final year mathematics undergraduate. It is split into three components: Computer Algebra, which teaches the use of Maple and Maple programming; Chaos, which teaches dynamical systems, deterministic chaos and fractals, with an emphasis...

The Magma package in Maple 15 includes the command IsSubMagma.  This tests whether a specified subset of a magma is closed under the binary operation that defines the magma.  For example, consider the following Cayley table for a group of order four.

> with( Magma ):
> m := << 1, 2, 3, 4 |

Time and time again you get caught up working with Maple and before you know it your 20 minutes of alloted time has turned into almost 1 hour.

Here's a little procedure alarm message to remind you it's time to start shutting down.  Start this procedure in a seperate worksheet and enter the number of minutes before you want your Maple alarm message popping up.  Open a new worksheet and start your work.  When the time is up, your message will pop up unless...

> restart; with(LinearAlgebra); assume(omega, real, omega > 0);
> G := 9;
> z := (xi^2+xi/(1+xi^2))/(1+xi^2);
`output redirected...`> print(); # input placeholder
> C := `<,>`(1-z, seq(sin((n-1)*Pi*z), n = 2 .. G));
`output redirected...`> print(); # input placeholder
> g := Transpose(C);
`output redirected...`> print(); # input placeholder
> A := Multiply(C, g);
`output redirected...`> print(); # input placeholder

> restart; with(LinearAlgebra); assume(omega, real, omega > 0);
> G := 9;
> z := (xi^2+xi/(1+xi^2))/(1+xi^2);
`output redirected...`> print(); # input placeholder
> C := `<,>`(1-z, seq(sin((n-1)*Pi*z), n = 2 .. G));
`output redirected...`> print(); # input placeholder
> g := Transpose(C);
`output redirected...`> print(); # input placeholder
> A := Multiply(C, g);
`output redirected...`> print(); # input placeholder

All too often one wants a list of dates from one date to another for use in a graph or table. 

All searches on the subject have evaded me.  I do not have Maple15 but I think the tools for such luxuries are there in the new Finance package. 

Without Maple 15, how can I do this in a simple manner?

** edit ** I have converted this to a post, plus added more info below

Well I have created a procedure with one way to achieve...

I am a mechanical engineering graduate student and I use Maple daily for everything from school projects to homework. Unfortunately, printing anything out (to hand in) either (a) ends up looking absolutely terrible / enormous or (b) takes forever to format. I have to go through and apply all of these styles I've saved that make all of the fonts smaller and a different color (and when I do that, things look weird.... powers are impinging on their bases [e.g. the x and 3 in x^3 are fused...

Russian MAC:
1.000.000 visits during the period June 2010 to April 2011

http://webmath.exponenta.ru/ege_11/d_04.html

At one point mapleprimes was fun and enjoyable ... until you get thumbed down with no explanation, it's really a kick in the teeth to see such things.  Because I see the thumbs down is still operational as it was to be removed.

This forum is not about some power trip and getting points thumbing people down or up and destroying the order of posts.  This is about sharing information and helping people get answers, if the answer is not good then let...

Inside a procedure, local variables are evaluated only one level. Of what good is this, one might ask?

Well, for one thing it allows you to do checks or manipulations of an unevaluated function call without having that function call be evaluated over again. I mean, for function calls to routines which don't happen to remember earlier results.

This is a revision of an Answer

Another feature added to Maple 15 partially in response to the MaplePrimes forums is the new/improved ?HTTP package.  It provides one-step commands for fetching data from the web: much simpler than using the ?Sockets package directly. In most cases, the command ?HTTP,Get is what you would use:

 (s, page, h) := HTTP:-Get("http://en.wikipedia.org/wiki/List_of_Crayola_crayon_colors"):

The above fetches the HTML source of a page from Wikipedia and stores it as a string 'page'. The other two outputs are 's', and integer HTTP status code and 'h' a table of the headers returned in the HTTP response from the server.  Compare this to the amount of code needed to fetch data in my Baby Names application for Maple 12, for example.

There have been some recent posts about interpolating data.

Attached below is a worksheet that shows some possibilities, with the functionality centering on the CurveFitting:-ArrayInterpolation command.

This is quick summary of parts of a broader document which covers both 2-d and 3-d methods (for regular grids), where I've left out the higher-efficiency methods and instead roughed in some examples involving integration and differentiation.

I've elected not to follow the 3-d Example from the ArrayInterpolation command's help-page, although using a pre-formed grid is a very fast approach to obtain just an interpolated 3-d plot. I also prefer to use the plots:-surfdata command rather than the plots:-matrixplot command, since the former let's one get the axes' tickmarks correct for the x- and y-data ranges.

The scenario is that you have a grid of data points in two dimensions (x- and y, or P- and T-, or what have you).

For each point (ie, for each 2-d pair of values) you have an associated value (or height in z, say). Hence you actually have data points in 3-d space.

How you obtained the associated (z) values depends on your own particular data collection method, or your own program. How you got the data is irrelevant here. What matters is that you have the finite number of data values, and no other easy way to generate data values at more points (let alone data for arbitrary new points). Below, we'll just create the data (once, at the start) for this example using an entirely made-up formula.

The presumption is that you might wish to plot a smooth surface that connects the 3-d data.

But you might also wish to write some program which requires interpolated (z) values at some new (x,y) 2-d points.  And you do not yet know what these 2-d point pairs are. So a pre-formed Array of points  at which to interpolate may not suffice.

Instead of using a pre-formed Array of output points, we'll contruct a procedure named `B` which can be supplied with a new (x,y) 2-d output point and (if that point lies within the original range) return an interpolated (z) value.

This procedure `B` can also be plotted, using the usual `plot3d` comamnd. It won't plot quite as fast as would a pre-computed and pre-interpolated finer grid of (x,y) values, but it should plot nicely. And the surface can be made quite smooth, by merely increasing the number of plotted points using plot3d's usual numpoints option. (Maple does not currently do "adaptive" 3-d plotting, so there's also no advantage in that respect.) But `B` does solve the secondary task, of being able to compute for any subsequent (x,y) point.

We can even integrate and differentiate `B` numerically. Of course we should keep in mind that this is somewhat error prone, since on top of usual issues with numerical differentiation there is also fact that we make the choice of interpolation method! The entire interpolated surface will differ considerably according to whether a spline, cubic (or other) interpolating scheme is chosen!

We'll use P and T as the x- and y- grid points, below, since "a name is just a name" and our choice of variables is arbitarary.

plot_interp.mw

Herbert A. Millington
Chair - Search Committee
412A Clarkson Hall, Whitson University
College Hill, MA 34109

Dear Professor Millington,

Thank you for your letter of March 16. After careful consideration, I regret to inform you that I am unable to accept your refusal to offer me an assistant professor position in your department.

This year I have been particularly fortunate in receiving an unusually large number of rejection letters. With...

25_04_2011.zip

From the work of the Russian MAC.
3.000 visitors a day, about 20.000 visits per day

http://webmath.exponenta.ru/