pchin

Dr. Paulina Chin

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18 years, 332 days
Maplesoft
Senior Architect
Waterloo, Ontario, Canada

MaplePrimes Activity


These are answers submitted by pchin

Have you tried the ExportMatrix command? In Maple 15, we updated the command to work with sparse matrices. It will take a Maple sparse matrix and produce a binary file which can then be read into MATLAB, again in sparse format.

Paulina

Currently, there is no way to set the frames-per-second value via a plotting command option, but we'll record this request in our database.

Paulina

In Maple 14, the following does indeed generate an error with the 2-d parser.

> proc()::integer; ... end proc;

This is a bug that we're working on fixing, and the fix should appear in a future Maple release.

However, the following is a different situation:

> proc(); local k; ... end proc;

In this case, the first semi-colon creates an empty statement appearing before the local declaration. Since local/global/option/description/uses clauses must appear before other statements, this should result in an error.

Paulina

Instead of increasing numpoints to a very large value, you can also use the grid option and increase the sampling for a particular dimension. For example, try grid=[30, 10, 10] with implicitplot3d. Unfortunately, the grid option seems to give an error when used with intersectplot. I'll record that in our bugs database.

Paulina

In Maple 14, the pointplot and pointplot3d commands were improved. Before Maple 14, these commands used lists internally and did expensive type-checking. Now, they accept Matrices having datatype float and pass them mostly unchanged to the renderer, resulting in better performance. As Tim suggested, you can use the ImportMatrix command to read in a test file and get a float Matrix. However, there is no longer any need to convert it to a list. You can pass the resulting Matrix directly to the pointplot or pointplot3d command.

Paulina

This behaviour doesn't seem to be directly related to 2-d input. If you enter table([]) in 1-d mode, you'll get the same behaviour. The 2-d math parser calls the table constructor, and that's why you see this unexpected output after entering a command in 2-d math. In any case, we'll look into this issue.

Paulina

The error that you see comes from the typesetting system, and it is unexpected. I cannot reproduce it when I run through the tutorial. It could be that the worksheet got corrupted somehow. I'd suggest you try closing the tutorial worksheet and opening it again. Let me know if you continue to see the error.

Paulina

Robert's response is correct. According to the LPSolve help page, "If the problem appears to be unbounded, LPSolve issues a warning and returns the last computed result. This result may be meaningless." We return the result with the warning, rather than just an error, because the result might still be useful information to the user, even if it is not the optimal solution.

Paulina

First, the view problem you see in Maple 12 was fixed in Maple 13. The orientation problem that Doug sees in Maple 14 is likely the same issue as the one described in this post. I expect that both examples will work correctly after the fix.

Paulina

Small values in the denominator are producing large radial values, so you are unable to see the part of the plot that's of interest. Try restricting the view with the coordinateview option, e.g. coordinateview=[0..10, 0..2*Pi]. For the last plot, also add the discont=true option to get the desired hyperbola.

Paulina

The difference is actually unrelated to the plottools[transform] command but has to do with differences between the 2-d and 3-d renderers. One of my colleagues passed on this response:

The reason the shading is different is that in the 3D case, grids are implemented as triangle strips – ie each rectangle is actually two triangles, and so the shading is interpolated separately on the two triangle strips, rather than as a function of all 4 vertices of the rectangular grid.

Paulina

This is a bug in animations, but it has already been recorded in our database and we're working on it. A fix should appear in a future release.

Paulina

The problem you're encountering is different from the one posted by Christopher2222. The cause of the error in your example is the evaluation of the Beta function, which is different from the Beta distribution. The Statistics[Distributions][Beta] help page has an explanation of this issue. An easy workaround is to replace Beta in your code with BetaDistribution.

Paulina

Currently, you cannot get hatched shading in a filled plot, but perhaps changing the transparency will help. See this post. You can get the second axis on the right-hand-side with the plots[dualaxisplot] command. If you don't actually want a second curve, you can just plot a point, for example.

p1 := plot(..., filled=[...]);
p2 := plot([[0,0]]);
plots[dualaxisplot](p1, p2);

Paulina

Try putting the most restrictive condition first. Evaluation of a piecewise is like that of an if statement.

T1:=piecewise(x>=30, 3.25*x*13/3+13, x>=20, 3.4*x*13/3+13, x>=0, 3.5*x*13/3+13);
plot(T1, x=0..40, discont=true);

Paulina

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