## 233 Reputation

12 years, 76 days

## Found the error...

I found the following post helpful http://www.mapleprimes.com/posts/41250-Using-DEplot3d#comment76752

hirnyk 469  has a good hint, but I was looking for a way to give a list of initial conditions, so that I can adjust to view the plot.

Based on this comment, I change my initial conditions as follows:

Then follow the syntax for DEplot3d:

## Oh Wow -- Strange, but works...

Thank you. It is a little strange, but it works!!!

## I like the points connected by line, and...

I used the following pointplot() command (listed below), and it still does not achieve the graph I'd like. I like the data points are connected by a line, AND the data points must be shown (or marked with a circle, or a diamond). I do not like the graph will only scatter points. === code stressStrainPlot := pointplot(stressStrainData, connect = true, symbol = circle, labels = [engrStrain, engrStress], color = red)

## Truly appreciate your help...

Hi Doug, Scott, and Acer: Thank you for all your answers; I've learned a lot from reading all the answers. ~ -- to work with elmentwise work fine Array -- work fine. Side notes: I had turned to MATLAB to get the answers quickly. I find MATLAB is a little more "intuitive" when dealing with array, list, vector; by "intuitive" I mean that users will not need to 'think' about "element operations". But I like the plotting features of Maple; I now come back to work on this problem using Maple. Thank you for your help. --mdc

## It works......

Did you suggest that instead of

1/4 * (sin^2(t) - cos^2(t))

I should use:

1/4* ( (sin(t))^2  - (cos(t))^2)

?

The error is rid of.  So, it is great.    Thanks

WRT: whether or not I get the answer I expect... I did not get the result I expect though.  I also use Stoke Theorem with surface integral, and the two integrals are not equal.  It is other problem.  Thanks.

## Found the problem...

With(VectorCalculus): was mispelled!!!

It is one very frustrating problem with Maple, its errors detection and error messages are very vague.

Thank you all for your help.

## Found the problem...

With(VectorCalculus): was mispelled!!!

It is one very frustrating problem with Maple, its errors detection and error messages are very vague.

Thank you all for your help.

## Thank you 4 time...

Hi Patrick,

Thank you for your time.  I will look into it further.

** I alwasy have restart at the top of my file

** I use Maple for Students.  I tried with With (Student[VectorCalculus]): and have the same problem.

Thanks

## I do have with(VectorCalculus):...

HI PatrickT:

I'm sorry for not being clear; but I do have with(VectorCalculus): in my .mw file; I neglected to mention.

Even with with(VectorCalculus): I still have the error

> r1 := diff(R(r, t), r);
Error, non-algebraic expressions cannot be differentiated
>

Any ideas?

## Error with diff (R(r,t),r)...

Hi Alex, I typed in what you suggested, I got the following error with the diff: > r1 := diff(R(r, t), r); Error, non-algebraic expressions cannot be differentiated > r2 := diff(R(r, t), t); Error, non-algebraic expressions cannot be differentiated Any suggestion? Thanks

## Parametric equation for a hyperbolic par...

Thanks, Pagan. Your comment gives me some insights to what I did wrong. Z = xy is one of the hyperbolic paraboloids. To parameterize it, the equation is: x=r*cos(t) y=r*sin(t) z=r^2*cos(t)*sin(t)

## Perhaps the parametric representation is...

Reading your explanations, I think the way I parameterize the surface z=xy is erroneous. i.e. x=cos(t) y=sin(t) is not a correct way to parameterize z, in this case. Ideas?

## Parametric equation of a surface...

In the past I was able to use plot3d or plot to plot a parametric surface. For example, if given a cone of z = sqrt(x^2 + y^2), I would parameterize it as: x = r*cos(t), y=r*sin(t), r and use plot3d to plot the surface of the cone. c := plot3d([r*cos(t), r*sin(t), r], t = 0 .. 2*Pi, r = 0 .. 2, axes = boxed, labels = [x, y, z], color = "Crimson") It works fine. The above error has something with the syntax, not the intention of my usage, I think. Idea?

## nvm...

I find the answer to my own question.

## Never mind...

I retyped carefully and do get the same value. (Sigh!!!). Thank you.
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