I would like to compute the Fourier transform of a impulse train for applications in signal processing.  I expect to get an impulse train as a result, but do not:

restart;
delta__t:=t->sum(Dirac(t-k*T__0),k=-infinity..infinity) assuming T__0>0
with(inttrans):
S:=fourier(delta__t(t),t,omega)

I will note that Mathematica has the DiracComb function since 2008.  It also computes the result as an impulse

train:https://reference.wolfram.com/language/ref/DiracComb.html which is what I would expect.  Is there something I should be doing that I'm not aware of?

Why is Maple not assigning values to A and B in the below example (Maple2018)?

restart;
assume(A < B);

S := 2/(B-A);
                                  2  
                           S := -----
                                B~ - A~
B := 10; A := 5;
                            B := 10
                             A := 5
S;
                               2  
                             -----
                             B~ - A~

I have been trying to figure out if there is any command in Maple where you can find the self-intersection points of a vector valued function in Maple? Other than having to type the equations manually into fsolve?  

Like shown in this 2013 post. 

https://math.stackexchange.com/questions/243065/self-intersection-of-vector-valued-function

Hi everyone

I have a partial differential equation in function u that contains conjugate of u. How can I write PDE like this in maple

PDE:=diff(u,t)+diff(u*,x)

where u=u(x,t) is complex function and u* is conjugate.

Why is it not as simple as

to obtain a result for the cubic root of -8 that is what one would expect: -2?

Instead we obtain

Why doesn't Maple return -2?

By printing each processing step for a parametric surface entered in 3-dimensional space,

i- Finding whether the surface is a ruled(regle) surface and printing it in the ruled surface form,

ii- Calculating the dispersion parameter of the surface and the throat line,

iii- Draws the surface and the throat line on the surface together,

When I run this code, I will get a error information:

CompositionSeries(SmallGroup(336, 209))

It's mean this function just work in transitive group? But IsTransitive(SmallGroup(336, 209)) will get true. Is it a bug of maple? Or do I have any misunderstandings?

Hi,

I am using the following (dummy) code to generate a density plot.

densityplot(x-y^2, x=-5..5, y=-5..5, axes=boxed, style=patchnogrid, numpoints=1000, legendstyle=[location=bottom], labels=[x, y]);

While this command does generate x vs y plots with varying color shared, I cannot figure out where the function (x-y^2) value by looking at the color shades. Is there a way to produce a legend along with the plot that will demonstrate how the function is taking different values with parameters? 

I found a similar post, dated 2005, that suggests using the "s_tyle=" command. However, it does not work for some reasons. I would appreciate help in this regard. 

Thank you,

Omkar

I know you can filter a dataframe by putting constraints on the numeric columns. However, I would like to sort and filter based upon a given string in a column, is this possible? I cannot immediately find this in the help files. Thank you for your assistance.QuestionDataFrame.mw

Hi MaplePrimes. 

I have a cubic with some parameters that I would like to solve and recieve 3 real solutions, however I cannot seem to find a way to get that to work while using assumptions. I always recieve 1 real and two complex conjugate answers. I have tried assuming the discrimant to be greater then zero but nothing seems to be working, and I have looked through a few posts on here but I cant seem to find anything out. In particular solve({f,conditions},{variable}) 

If I solve with a known set of paramters(which i determine graphically) that gives three solutions everything works fine. Also if I solve the cubic generally and recieve the two complex solutions and one real then substitute the paramters in I get the same correct answers, so I am slightly baffled. If I have missed something simple my apologies. 

Any help would be greatly appreciated. File attached. 

CubicSolve.mw

HI, I have numerically solved the given problem using the dsolve command But I want to solve the same problem using the Differential transformation method.
Can anyone help me to get the series solution for the given problem using DTM.

I want to compare the numerical results with DTM results when lambda =0.5.

eqn1 := diff(f(eta), `$`(eta, 3))+f(eta)*(diff(f(eta), `$`(eta, 2)))-(diff(f(eta), eta))^2-lambda*(diff(f(eta), eta)) = 0.

eqn2 := diff(theta(eta), `$`(eta, 2))+f(eta)*(diff(theta(eta), eta))*Pr = 0

Bcs := (D(f))(0) = 1, f(0) = 0, (D(f))(infinity) = 0, theta(0) = 1, theta(infinity) = 0;

[lambda = .5, Pr = 6.3]

Evaluating this integral

produces an infinite product as output. Why does Maple not automatically simplify to infinity. Can the extra information (1+pi) be of any use?

Download Infinity_times_something.mw

Please how can I define two sequences in a procedure with two arguments?

  ans:= Array([seq( [j, doCalc(j, u)], j=-2..0, 0.006, u=1..334)]):

The procedure is doCalc(j,u)  and I received this error: invalid input: seq expects between 1 and 3 arguments, but received 4

Find attached my complete code.Seq_Proc.mw

Good Morning Guys,

Please, could somebody help me with my problem in Maple?

The expression y' = y^4 * cos(x) + y*tan(x) with start-value y(0) = 0.5 has the solution of 1/root(cos(x)^2 * 8*cos(x)-3 * sin(x),3).

If I try to solve it with this method dgl_2 := diff(y(x), x) = y(x)^4*cos(x) + y(x)*tan(x) I don't get the right solution. Is it possible to solve this expression with a Tutor app? step by step? If yes I would so happy to tell me how I can do that. 

Thanks a lot and I wish you all a nice sunday and stay safe.

Is there a way to importing cell values as text, and not numbers, when the cell is formatted as a text?

As far as I can see, a cell with the value "1" is always import as "1.0" in ExcelTools, regardless if the cell is formatted as text or something else in Excel.

Writing '1 in the Excel cell however leads to a text import in Maple, and will give "1", not "1.0".

There is one more thing that is strange in Excel. Even if the cell is formatted as a text, or the cell content is with a ' before the number, Excel will allow a calculation with that value. Text value 4 will give 5, if added 1.