## solving for listprocedure result of dsolve...

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i m calculating space of this elipse,i need to find point t1 wherein [XX(t1), YY(t1)] creates full circle and get S(t1). here its between 22.6-22.7. but i need to find it with ~0.1^3  accuracy.

for_clever_guys.mw

## How to make Maple18 return the accurate value?...

In the old version of Maple, the accurate value of Sin()and Cos() at some particular points, such as Pi/10, can be returned as below:

But in Maple 18, it just returns the same as the input.

How to make Maple18 return the accurate value as before?

## How to simplify this result from the ODE solver wi...

Here is the ODE:

dsolve((y(x)^2-x)*(D(y))(x)+x^2-y(x) = 0, {y(x)})

And the Maple 18 returns a very complex result.

But as we know,the more elegant result should be this:

How can I get this simple result with Maple?

## pointplot3d symbol=point .. no points...

with pointplot3d and 14,000 points when I enter symbol=point I get an empty plot.

Only when I set symbolsize=1 (a point) do I get points appearing in the graph.  Bug?

## Having Problems with dsolve - Error, unable to mat...

restart;
Eq1 := diff(T1(t), t) = (W*Cp*(To-T1(t))+UA*(Ts-T1(t)))/(M*Cp);
Eq2 := diff(T2(t), t) = (W*Cp*(T1(t)-T2(t))+UA*(Ts-T2(t)))/(M*Cp);
Eq3 := diff(T3(t), t) = (W*Cp*(T2(t)-T3(t))+UA*(Ts-T3(t)))/(M*Cp);
sys := Eq1, Eq2, Eq3;

Operational Veriables

W := 100;
UA := 10;
Cp := 2;
M := 1000;
To := 20;
Ts := 250;

Initial Conditions

sys1 := {Eq1, Eq2, Eq3};

nsys := nops(sys1);

ics := {T1(0) = 20, T2(0) = 20, T3(0) = 20};
{T1(0) = 20, T2(0) = 20, T3(0) = 20}
nics := nops(ics);
for i from 1 to nics do Sol ||i:=dsolve({sys1, ics[i]},{T1(t),T2(t),T3(t)},numeric)od;
Error, unable to match delimiters
Typesetting:-mambiguous(Typesetting:-mambiguous( for i from 1 to

nics do Sol verbarverbariAssigndsolvelpar(sys1comma ics(i))

commalcubT1(t)commaT2(t)commaT3(t)rcubcommanumericrparod,

Typesetting:-merror("unable to match delimiters")))

## mem usage maple.exe in task manager when high caus...

I was running some wav files through the spectrogram increasing the fft window size.  Generally just playing around.

I have run into an issue.  After running a few times the mem usage for maple.exe starts to run high.  I get it up to 600,000 K and still seems to run okay - ie able to produce a spectrogram.  However running it again at a higher window size of course eats up more memory and right around 1,000,000 K mem usage everything slows down and it appears to freeze.  The spectrogram is not displayed, after a short while CPU usage drops to zero the heartbeat circle (evaluating symbol - bottom left corner) stays solid and everything appears to stop.

It is possible to close the worksheet in the same maple session after some time and open a new one.

Another note.  After one worksheet has ramped up the mem usage to a large value say 800,000 K (it doesn't really matter) .. when I close the worksheet (in the same maple session) the mem usage remains high even after a restart;gc():   I not sure if this has been normal throughout the ages, but I thought after closing a high mem usage worksheet in the same maple session the mem usage in the windows task manager would have updated back down under 100,000 K at least.

The system Maple is running on right now is a P4 3Ghz Windows XP at 2.50 GB RAM Maple 18.00 stnd GUI 32 bit.  Using the spectrograms example in the application center for start.

Any insight as to why the computer starts to freeze up around 1,000,000 K mem usage would be helpful.  Also why closing a worksheet had no effect on the mem usage.  Would be interesting to know if this occurs on other machines as well.

## Another (maybe silly) question on a procedure...

As I stated in an earlier post, I'm new at this.

I'm trying to write a procedure to calculate what is called a "crescent latitude". The full formula can be seen here: https://db.tt/QAUzH5i0.

b is equal to 0.081819221; it takes a single parameter φ (latitude of a location in degrees)

I normally get errors like unable to parse, unable to match delimters, etc. and the result is the name of the procedure and whatevere value of the parameter I put in parenthesis, not the calculated value.

Anybody can help?

Thanlk you

Martina

## How do i obtain lie symmetries for this type of pa...

https://www.dropbox.com/s/r7xn2uqnn4qfbp7/Screenshot%202014-05-12%2015.21.07.png

## Units conversion problem...

This is an addition to the following post:

http://www.mapleprimes.com/questions/141795-Unit-Conversion-Problem

But I use the clickable facilities of Maple.  Here is the problem:

>32[[degC]];

32[[degC]]
right-click -> Units -> Replace units -> degF

288
--- [[degF]]
5

>evalf[5]( (2) );
57.600[[degF]]

but if I do that:

>convert(32, 'temperature', 'degC', 'degF');

448
---
5

>evalf[5]( (4) );
89.600

Why the conversion is bad when you try to do it by the clickable way????????????

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

## 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.

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