Maple gives solution to PDE which does not satisfy...

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Do you agree this solution given by Maple is not correct?

restart;
pde := diff(u(x,t),t)+diff(u(x,t),x)=0;
bc  := D[1](u)(0,t)=0;
ic  := u(x,0)=exp(-x^2);
sol:=pdsolve([pde,ic,bc],u(x,t)) assuming x>0,t>0;
pdetest(sol,pde)


Result of pdetest should be zero.

I think the PDE itself is not well posed (I copied it from different forum to see what Maple does with it). But still the solution clearly does not satisfy the PDE itself for x not zero.

Maple 2019.2.1 with Physics version 573

Is it possible to create variables of some type wi...

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Hi,

It seems to me that variables (maybe I should have use 'names' instead) become "typed" only once they have been instanciated with ':=' ?

But is it possible in Maple  to do something like that
"I declare that variable V will be of type T even if I do not explicitely instanciate it?"

... or is it here one of the distinction between a "typed CAS" and a "non typed" CAS ?

Thanks in advance

NLPSolver, non-numeric result encountered...

Asked by:

test.mw

Please see the attached.

NLPSolve('f(x,y,'g(x,y)')', x=0..1,y=0..1) is not working...

file name on excel export ...

Asked by:
 with(ExcelTools):
 > Export(R,"𝙴𝚖𝚙𝚕𝚘𝚢𝚎𝚎𝚜.𝚡𝚕𝚜","𝙿𝚊𝚢𝚛𝚘𝚕𝚕","𝙱𝟸")

----------------

how to make the export excel file take his name from variable ?

for example

V:=800;

so the export file will make name as 800 , and so on |?

for loop inside unapply...

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How to use for loop inside unapply operator

plot3d in Maple 2017 and 2019...

Asked by:

test.mw

I am not sure why I cannot do: plot3d([f(x,y,'g(x, y)')], x=0..1,y=0..1).

And the use of single quote in Maple 2019 and 2017 are giving different results. that is, the plot (note, not plot3d) results in the attched script by Maple 2017 and 2019 are different...

sqp minimization methopd maple...

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I want to know whether sqp method do a local search or a global search. Thank you.

why I can't isolate the negative sign from odd rad...

Asked by:

I found that i can use  simplify under assumption to gain the result :

simplify((-p^3)^(1/3), assume = negative);
-p

simplify((p^3)^(1/3), assume = positive);
p

But confusing ! I expected the simplify command just with the option=symbolic works at the same manner ?

My purpose :

 >
 (1)
 >
 (2)

Without negative sign the simple symbolic result appears :

 >
 (3)

In power 3 the Imaginary part is included too !

 >
 (4)

NOT WORKING !

 >
 (5)
 >
 (6)
 >
 (7)
 >
 >

Download odd_negative_powers.mwodd_negative_powers.mw

I try to invert this Matrix and get error...

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Way I get this error ?

 >
 >
 >
 (1)
 >
 (2)
 >
 >

Download matrix_inversion.mw

Asked by:

Compute sequences of functions easily...

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I create a lot of procs and functions and then find myself having to create sequences of their values. I use for loops, seq or create a new proc to do it.

e.g., suppose I have a proc like f := n->n^2 or whatever. I can do [seq(f(k),k=0..5)]. Is there a very simple notation that maple has to do the same? E.g., hypopthetically f(0..5) and it handles the accumulation in to a sequence itself

How to stop maple from rewriting equational form...

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e.g., I have an equation that is written like a/b*c and maple rewrites it as a*c/b.

c is a complicated expression and when it's written with b under it, it takes up far more vertical spaces than necessary giving less visual resolution even if b is just 2.

In latex notation it is the difference between \frac{a}{b} c and \frac{ac}{b}.

In general what is the process? I noticed I can sometimes use   to block things in but this also interfers with mathamtical notation. e.g., 3^f becomes just that rather than f writen as a superscript.

Clearly I could hack it using various things but I want something direct and simple that tells maple not to try to do it's magic tricks.

For example, sometimes I might have 2*(a + b) and maple displays it as 2a + 2b. If I write it as 2*(a+b) then this is noted as 2*(a+b) but the 2 is different.. I guess it is treated as a string or something... For my cases it works since I'm not trying to calculate anything from the expression but just for visual purposes, other times though I might want to calculate(usually the visual doesn't matter in calculation but sometimes both are desired).

I really want to avoid having to litter the expressions with special syntax to get such simple behavior. Something to tell maple not to carry out whatever algebraic transform it is programmed to do.

BTW, what does ! do? !3 + 4 opens a new window with an exit code.

Problem collect with distributed ...

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Hello,
the following command

collect(c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel, [nur, nub, dnur, dnub, nurdel, nubdel, dnurdel, dnubdel, c4], distributed)

returns

c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel

However, I am expecting it to return

c4*kpbr*ksr*(dnub*nur*nurdel+dnur*nub*nurdel)

Where is the error?
Thanks in advance

Coefficients of expressions...

Asked by:

Hello,

Lets say I have an expression

f:=(a+b)*x1+(a^2+b^2)*(x1+x2^2)+c*(x2-x3)*a*b

and I have a list

p:=[a+b,a^2+b^2,c*b*a].

How can I get the coefficients of the element from p in f, ie,

cof=[x1,x1+x2^2, x2-x3].

such that cof[i] corresponds to p[i]?

Thanks in advance for your suggestions.

How do I remove these unwanted trailing zeros from...

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How do I remove these unwanted trailing zeros from my plot ? I have tried setting striptrailing=true from the Tyesetting package but no difference. Thanks

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