# Items tagged with notnot Tagged Items Feed

### DEplot: Plot not appearing when doing a phase plot...

March 07 2013
1 2

Hi

I am trying to do a phase plot of an autonomous system using DEplot command. However, no phase plot appears. Could you tell me what am I doing wrong? The same code worked for my professor in class, but it's not working for me. I am using Maple 16. The code is posted below.

> with DEtools

> sys := diff(x(t), t) = y(t), diff(y(t), t) = x(t)*(1-x(t)*x(t))+y(t);

> DEplot([sys], [x(t), y(t)], t = 0 .. 0.1e-8, x = -3 .. 3, y = -3 .. 3, color = black)

### Assignment using old version of question bank...

January 23 2013
0 0

I've several versions behind but I getting a strange behavior. I created an assignment using the eco0 question bank. Later this assignment was passed to a class a semester later. The question bank eco0 was updated. As the instructor, using the review button on the assignment shows the new version of the question bank. As a student, the assignments are getting the old question bank question.  The students didn't start the assignment until after the questionbank change.(I think I'm using version 4.0.)

### Diagramm: Fit a function one some measured points ...

March 14 2012
0 6

HI,

I measured some points. This points are plotted in a graph. Now I want to make a fit on this points.

I now that the fit-function has to be like this:

F = A + B1 x e^(-t/C1) + B2 x e^(-t/C2)

Problem: how can I create a fitting function like that?

The best thing I found is the "spline"-fit, but it doesn't work properly. It has to be one lonely function, not a summary of several functions (like spline).

December 19 2011
1 1

Hi, I use maple 12 for mac, I have an exam at 9am, it's almost 3am and my whole exam notes (open "maple" exam, as opposed to open book) have just corrupted.

2p81_final.mw

### Units Package doesn't handle Celsius to Kelvin?...

October 13 2011
0 3

I put Celsius in my equation and I get the wrong answer even though I've loaded the Units Package:

I have to put in the conversion to Kelvin by myself to get the right answer:

What am I doing wrong?

Edo

### why does evalc give csgn?...

July 17 2011
0 1

Hi,

I am trying to simplify the expression s as given below. (I am not sure why it comes up with all the vector caclulus notation in it but it should display okay when you enter it)

Because of the presence of the exponential imaginary fucntions I thought evalc might be useful but when I use it I get a huge expression with csgn appearing in it. To my knowledge csgn appears when assumptions are not correctly specified - is this so? I can't see any assumption...

### Extract the argument of a trigonometric function...

February 14 2011
0 3

Regards,

I have a very large equation which has an arctan(x,y). I need to be able to extract the arguments x,y and assign them in some variables.

I have tried the solution given here.

Unfortunately, that solution only works for constants, not equations.

For example, if I use the proc given in there with arctan(10,11) it works. But if I use something like arctan...

### do function in maple...

November 27 2010
0 3

Hello everyone,

I have a great problem with maple (cause I'm a beginner)  My problem is When i write the following
for i from 1 to M do x[i]=evalf(a* cos(t[i])) end do;
I get a numbers for x[i], like t[1]=0, then x[1]=3.
until now no problem.
But when i calling x[1] in another place in the same file. i get x[1]=0.
Could any one help me.
Amr

### Maple 11 does not save...

October 22 2010
0 3

I setup Maple 11 on windows 7   but the program does not save any data

### last action not updating...

July 26 2010
0 0

A recent comment addition of mine adding comments (in parse lists) did not update the last action in the thread, there is a 3 hour difference.

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