Hi guys, 

I need help with differentiating a function I have defined. Here is the function I have:

The right hand side of this expression is a solution I have previously found via Maple, I know that this is correct. Basically I have a function a that is dependent on the another functon u(x,y,t).

Now the way I have defined this gives me the RHS of the above equation which is what I want. However, what I now need to do is to show that this constant function _F1(x,y,t) is equal to zero. I know this to be true via hand calcuations, but to do so I need to sub it into another equation where it has the derivatives of a. The way the derivatives are defined is through the D function. But this doesn't seem to work with how I have defined the function previously.

D[1](a)(x, y, t, u(x, y, t), diff(u(x, y, t), x), diff(u(x, y, t), y), diff(u(x, y, t), t), diff(u(x, y, t), x, x), diff(u(x, y, t), y, x), diff(u(x, y, t), x, t), diff(u(x, y, t), y, t), diff(u(x, y, t), t, t)) 

This should give me 

-4*diff(u(x,y,t),x,x,x)+diff(_F1(x,y,t),x)
However it just repeats what I input. I have tried defining the function in a different way,

a:=(x, y, t, u(x, y, t), diff(u(x, y, t), x), diff(u(x, y, t), y), diff(u(x, y, t), t), diff(u(x, y, t), x, x), diff(u(x, y, t), y, x), diff(u(x, y, t), x, t), diff(u(x, y, t), y, t), diff(u(x, y, t), t, t)) ->-4*diff(u(x,y,t),x,x)+_F1(x,y,t)

However this returns an error where I am not allowed to define this.

Can anyone help, would be a massive help. Thanks in advance.

What wouldn't work in Maple 2018 if I removed the Microsoft Visual C++ 2015 redistributable?  I have older versions of the C++ redistributable packages (ie 2013).  I hadn't noticed anything unusual when I initially removed it but maybe there's something that's affected in Maple?  Code generation package routines maybe?  What commands in Maple would be affected?

Reason is, I'm getting errors with another software and re-installing the 2015 C++ redistributable isn't installing properly.  So I'm just hoping there's no issues using Maple without the C++ 2015 redistributable being installed properly. 

Hi,

Here is my code:

###################

f:=x->piecewise(x>=-1/2 and x<=1/2,1):
eq:={diff(x(t),t)-sum(f(t-k*T),k=0..K)*x(t)=0,x(0)=0}:
sol:=dsolve(eq, numeric, parameters=[T,K]);
sol(parameters=[1,20]);
############

And the result is an error I cannot solve:

Error, (in dsolve/numeric) the following unknowns appear in the system, but are not specified as parameters: {k}
 

Then, how to modify the code?

Best regards

Jaqr

Dear sir i want to display only three curves 1, curve 2 curve 3  in legends but in the plot it should be nine curve a sampe codes and a sample graph is attaching , please give suggestions. Here is my codes 

h:=z->1-(delta2/2)*(1 + cos(2*(Pi/L1)*(z - d1 - L1))):
K1:=(4/h(z)^4)-(sin(alpha)/F)-h(z)^2+Nb*h(z)^4:
lambda:=(F,Nb,delta2)->Int(K1,z=0..1):

L1:=0.2:
d1:=0.2:
alpha:=Pi/6:
A:=plot( [seq(seq(lambda(F,Nb,delta2), Nb=[0.1,0.2,0.3]), F=[0.1,0.2,0.5])], delta2=0.02..0.1, linestyle = [solid,longdash,dashdot],'thickness = 2',color=[red$3,blue$3,black$3]):

B:=plots:-textplot([[0.05,-1,F=0.1],[0.05,1.5,F=0.2], [0.05,3,F=0.5]], font=[times, 14]):

plots:-display(A, B);
 sample graphs 

Hi All,

I would like to plot3d a function say z=f(x,y). x=0..1, y=0..1.

But I only want to display a surface of the plots, say z=0.1. Is there any simple function to do that?

I am looking for soemthing like: plot3d(f(x,y)=0.1, x=0..1,y=0..1)

thanks.

Is it possible to split an execution group containing 2D input?
(without conversion to 1D which destroys the format).
Using F3 or the menu seems to work only for lines with a prompt.
But usually an execution group has a single prompt; lines with prompts appear e.g. when two execution groups are joined (with F4).
Is copy&paste the only solution?

Hi!

I am trying to export the plots I generated into black and white images. Currently, I am trying to use a proc as:

ExportFunctionPlot := proc(p::evaln, pname)
    local name, place, opts:
    name := cat(pname, ".eps"):
    opts := `landscape,width=768,height=768,noborder,axes=boxed,color="Black"`:
    plotsetup('eps', 'plotoutput'=name, 'plotoptions'=opts):
    print( plots:-display( eval(p), 'axesfont' = [ TIMES, 30 ],
                        'labelfont' = [ TIMES, ROMAN, 30] ) ):
    plotsetup(default):
end proc:

However, the eps files I got still have colored lines. Is there any way I can export to just black and white eps images?

Thanks!

William

Hi All,

I am thinking is there any simple function that could extract part of the points that have been ploted by plot() or plot3d(). And more ideally, we can specify some constraints such that the points being extracted must satisfy.

I guess Maple must stored the points somewhere in the memory in some kinds of data structure....

thanks.

I have a system with unknown functions: R(x), mu(x), Y(x). I need to find them AND also mu'(x), Y'(x), Y''(x). How do I write it in the code?

I tried something like this:

F := dsolve({cond, sys}, [R(x), mu(x), Y(x)], numeric, output = listprocedure);
Y1 := eval (Y(x), F);
Y2 := x -> diff(Y1(x), x);

It works, but does it work correctly? Y1 is a massive of numbers, is it correct to write "a derivative from a massive of numbers"?

I also tried this:

F := dsolve({cond, sys}, [R(x), mu(x), Y(x), diff(mu(x),x), diff(Y(x),x), diff(Y(x),x$2)], numeric, output = listprocedure);
Y1 := eval (Y(x), F);
Y2 := eval (diff(Y(x),x), F);

But it doesn't work at all and gives me an error on F: 

Error, (in dsolve/numeric/process_input) dependent variables must be functions of a single unknown, the independent variable. Got [diff(Y(x), x), diff(diff(Y(x), x), x), diff(mu(x), x)]

How should I really do it?
3.1.mw
3.2.mw

I am seeking the limit of a series representation of a waveform to within so many significant figures.  Unfortunately, as the series contains more & more terms the demands on computation memory become a problem.  Perhaps there is a method within MAPLE I am not familiar with that can possibly circumvent this problem?

Below is the link to my worksheet.  The presumed theoretical limit is supposed to be 0.0894945 (this is based on what I have read)  (perhaps it may be wrong).  So far I have 3 of the sig figs agree, but would like to take it further.  Is this possible with different MAPLE commands than what I am currently employing?  Currently, MAPLE crashes if I venture beyond 100000 terms in the series.

seeking_the_limit.mw

Hi All,

I would like to generate a sequence (say 10) of points <x_i,y_i>. (i=1, 2,..,10.)

There is a predefined constraint like f(x_i,y_i)=0.01. And I don't know the close form of f() (becasue there is a intermediate parameter in f() that was caculated numerically by optimization.).

Is there any simple function, e.g. a variant of seq(), that can do this? I am looking for something looks like:

seq(f(x,y)=0.01, x=0..1, y=0..1, 0.1)

Thanks.

Ok for some reason Get-Property doesnt work here but it does in another worksheet but anyway that problem isnt really what im posting for help for, i want general advice on the asthetic lay out of education tools.

The example i am doing tonight is pretty standard, i want to have a window where the student can play around with the recurrence relation making little alterations as he or she is curious about,  then hit a button to produce the first N values of the sequence, but see the problem i always get is that i dont care how messy or easy to use anything is because i am the one that wrote the code, so the features of such an analysis tool are redundant in the fact that i know how to use maple to a reasonable extent, but i want to make education  tools that are focused purely on the mathematics, removing the programming and all of that nonsense from the students focus here, so, i need advice for this given this stated objective.

Also forgot to mention, i already know how to get all the embedded components working together, this part isnt the problem i am referring to. I mean to say how can i best present the interface of these tools given what i can make in maple.

Download MAPLE_HELP_RECURRENCE_SEQUENCE_ANALYSIS_TOOL.mw

I was recently cleaning up a worksheet to make things more succinct.  In that process I modified how I expressed the series coefficients, Ck.  What seemed to be an innocous change apparently upset MAPLE to the point it cannot process my results.  In the abbreviated worksheet link below I process the results in the previous manner, Ck1, as opposed to my current modification, Ck2.

In the previous manner the results are generated under 3 minutes.  After modifying the expression for Ck, MAPLE cannot seem to process the results at all.  As far as I can tell the Ck1 & Ck2 concur.  So I am perplexed.  Can anyone see what is wrong?  The only thing I can think of is that sin(2*pi*k/T*x) in the denominator might cause the problem.  However, the sin term is cancelled out by the same sin term in S4.

Ck_modification.mw

Probably I am overthinking this but in any case I have hit a road block. If anyone can point me in the right direction I woould greatly appreciate it! Peter_Ursa.mw
 

Download Peter_Ursa.mw

Hello everyone,

  How do I go around this PDE. I think I have input all the necessary required but its given the error code "Error, invalid input: subs received [beta = .5, v = .5, v__l = 1.0, eta = 1.5, false], which is not valid for its 1st argument". 

Below is attached the code.

pde.mw

Please, anyone with any information should help. Thanking you in anticipation.