## Why can't Maple solve this simple ODE??...

ode := diff(sqrt(U(t)), t) = sqrt(U__0)-sqrt(U(t))

ics := U(0) = 0

dsolve({ics, ode})

And the result maple returns is U(t)=0 !

## General solution for differential equations...

Diff_EQ_sample_questions.pdf

This is a link to two sample questions I am trying to learn how to solve using maple. I am using maple student edition of maple. Any help would be great. Thank you.

## Error, (in dsolve/numeric/bvp) initial Newton iter...

im solving 6 ODE which is the equations are unsteady with boundary conditions.. the program can be run when A=0 but when A=0.2 or others value .. its cannot be run... A means for unsteadiness... before this i solve for steady equations.. this is first time i solve for unsteady using maple.. anyone know where i am wrong??? thanks for helping :)

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## How to do 3D data visualization in Maple?...

Several years ago, I used to plot, in Maple 7 I think, 3D scalar functions by using procedures to create a 3D mesh and populate the data points before I could use plot3d.

I wonder if there is a more convenient (least coding) way to do it today? Consider for example f(x,y,z) = x^2 + y^2+z^2

A way to visualize a number of concentric isosurfaces of f is to loop with (is there a tag to write this in code block?):

for i to 10 do iso[i] := implicitplot3d( f = i, x = -10 .. 10, y = -10 .. 10, z = -10 .. 10) end do

display(seq(iso[j], j = 1 .. 10))

Of course, visualizing the output is another issue.  I wish for an app to explore 3D data like Paraview. It does not have to be as sophisticated, but to display standard elements like isosurfaces and arbitrary cutting plane views would suffice.

If you know a package/app/procedure in Maple of this nature, please share it here. Thank you

## Printing Western European characters from inside a...

Sorry if this has been already posted.

When print() is invoked from a proc into a module, non-English characters are not properly displayed with Maple 18.

It works ok if it is invoked from within the workbook.

Example:
print("Están en perspectiva")

Put this sentence in a proc into a module and the character "á" wont be displayed

Output: "Est�n en perspectiva"

Any hint about how to treat this issue?

Thank you very much.

## faster numeric Bessel functions

by: Maple 18

Some years ago member William Fish started a long discussion in part about a numeric integral involving high parameter (high oscillation) Bessel J0. That numeric integration task appeared in a Bitwise Magazine article.

At that time even obtaining numeric results involved extra effort such as handling real and imaginary components of the integrand separately, and requesting particular methods (sometimes hacked, to bump up the subinterval limit, for very high parameter values).

That led to a post where I showed that the result could be obtained quickly by using a fast compiled BesselJ (J0) from an external library along with a modified low-level call to a particular evalf/Int solver.

And sometime after that a numeric result for the real & imaginary split integrand became much more readily (if not quickly) available by using a new `maxintervals` option of evalf/Int to specify the maximal number of subintervals for the particular solver.

Maple 18 has its own compiled implementations of the Bessel functions for "hardware" (double) precision arguments. So now the numeric evaluations of the integrand are computed much faster.

Using Maple 18.00 on 64bit Windows 7 the same numeric results obtain in under a second, in a simple, single call to evalf,Int.

```restart:

CodeTools:-Usage(
evalf(Int(BesselJ(0, 50001*x)*x*exp(I*(355*x^2*1/2)), x = .35 .. 1))
);
memory used=9.28MiB, alloc change=32.00MiB, cpu time=437.00ms, real time=441.00ms, gc time=0ns

-8                 -8
3.181753502 10   - 7.798301124 10   I

restart:

CodeTools:-Usage(
evalf(Int(BesselJ(0, 10000*x)*x*exp(I*(355*x^2*1/2)), x = .35 .. 1))
);
memory used=6.83MiB, alloc change=32.00MiB, cpu time=218.00ms, real time=211.00ms, gc time=15.60ms

-7                 -7
-2.007752340 10   + 4.275388462 10   I
```

Of course the ramifications of fast, compiled Bessel functions at double precision extend much farther than just this one example. But I like seeing the speed improvement in terms of a concrete example.

acer

## Writing out a problem set in on the computer...

For solving problem sets, I have a pdf template I created for myself that has a header with a blank for the class name, TA, professor, date, etc. In addition to this header, I had a margin on the left to scribble questions I had and to holepunch.

I used to print out the template and write on the template and turn in that as my pset.

I am nowthinking of doing everything on the computer. Writing out all of the problem set on the computer. Combining stuff from maple, combining handwritten stuff from the computer using a digitizer. However I want to write it all on top of the my template that I created, which is a pdf file. I can turn the pdf into an image file if need be.

What would be the easiest way to do what I want? To open a program that automatically sets that pdf as the template and easily lets me handwrite stuff I want and paste in maple code?

Right now if I tried my idea, I would basically be constantly copying and pasting stuff from maple and my digitizer drawn pictures/equations into one file and it would be very clumsy.

Basically there are problems that I do partially on maple and I just want to unify all my work into one easy, printable file.

## Symbols, subscript and superscript in Maple 18...

Hello,

I am a student and using Maple to type homework assignments because of the math symbols available.  I was using Maple 17 but upgraded to 18, and its not as easy to use as 17.  For right now I am using it in text mode, because that is what I need.  But I can't figure out an easy way to do subscripts and superscripts in text mode.  Also, the "element symbol," where is it?  I feel like a lot of stuff is missing.  For instance, the arrows, the sideways triangle, lots of symbols I used before the upgrade I cant find.  Can someone help please???

## Arrangement of indices after Simplify...

After using Simplify the indices are are arranged in the tensor.  I am using the April 14th update from the Physics R&D page.

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We first define the Christoffel symbol in terms of the metric,   .

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Now we can substitute into the null condition for the Ricci tensor, .

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Do the first term

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Do same thing with the first term but use the Simplify command

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Simplify command does make the algebra easier, but the indices are not the same. Now, equation 16 should correspond to equation 14, but there is no combination of alphas that is consistent.  The variables alpha1 and alpha5 must be rho. One term is always wrong when I try to change the other indices.

alpha2 and alpha3 must be either mu or nu based on the first term.  But alpha6 should also be either mu or nu based on the last term, however that will make alpha2 and alpha3 either (nu and rho) or (mu and rho).  Neither combination makes all of the terms consistent with (14).  Very frustrating.

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## Advice sought on making input to a 3-d printer usi...

I have just begun thinking of trying to make some mathematically defined objects using a 3d printer. I would be happy to hear from anyone who has done this using Maple to prepare input. Pointers for a novice in 3d printing would be appreciated.  I have access to a MakerBot Replicator 2. But the people who have it have only used it to scan objects and make 3d copies of them.

---Edwin

## Error, (in dsolve/numeric/bvp/convertsys) too few ...

im solving 4 ODe with boundary conditions.. i got this error Error, (in dsolve/numeric/bvp/convertsys) too few boundary conditions: expected 8, got 7

## WHERE CAN I FIND CLICKABLE PHYSICS CLASSES IN ENGL...

You have clickable calc. Today I saw in your email that you have clickable physic but in french. Do you have it in english too>?

Thank you

manolo

## mtaylor expanssion...

Hello,

I have this expression on image below and I would like to do multi taylor in these variables. The maple says that the expansion is not possible to do. Does somebody know where the problem could be ? Thank you very much for help.

Equation:

Taylor series:

## How to plot a graph...

i solve 4 ODE with boundary condition.. i try to plot a graph F(eta) with different value of M.. but it doesnt comeout.. anyone can help me please??

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## I am so close to plot what I need but......

Hi everybody,

In quantum mechanics, I want to draw the wave  of the electron in the hydrogen atom.  So in 3D, you will have a cricle and along the circle, there will be a cosine function that will meet after a full cercle (the standing wave that is possible).  The blue one and the red one at the same time.  But in 3D

The closest that I come to succes is with this commands:

But as you will see, the wave end at the same place as it started.  But instead of going in a cercle, is as a funny shape.

Thank you in advance for you trouble.

```--------------------------------------
Mario Lemelin```
```Maple 18 Ubuntu 13.10 - 64 bitsMaple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```
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