MaplePrimes Questions

Hello my friends

I want to solve first order non-linear differential equation by maple 2018 but it does not give me the explicit form for a(t) as the function of time t.

this is my equation where z,k,c, and w are non zero constants 

3*a(t)-a(t)^2-3*z*(diff(a(t), t))^2+k*c*a(t)+w/a(t) = 0

please guide me.

with the best regard

Hi

I would like to designate AU as currency for my application, rather than the USD.

I can do it to a degree, but when I use combine I have problems. Compare output 8 and 9 to 17 and 18. help?

 

CURRENCY.mw

I'm presently interested in PDE and I have just discovered the impressive work Nasser Abbasi,has done, and keeps doing, concerning the solution of PDE benchmarks with Maple and Mathematica.
https://www.12000.org/my_notes/pde_in_CAS/pdse3.htm

It seems that the result Maple returns for the test case below is not the general solution.

  • 4.19 first order PDE of three unknowns
    problem number 19
    (from example 3.5.4, p 212, nonlinear ode’s by Lokenath Debnath, 3rd edition)


It is rather simple to see that any spherical function u(x, y, z) =f(x^2+y^2+z^2) is a solution of the PDE.
Then any function of the form u(x, y, z) = f(x^2+y^2+z^2) * exp(x+y+z) *C1 (C1 being any constant) is also a solution.
Maple returns only the solution u(x, y, z) = exp(C2*(x^2+y^2+z^2)) * exp(x+y+z) * C1


 

restart:

u := (x, y, z) -> f(x^2+y^2+z^2)

proc (x, y, z) options operator, arrow; f(x^2+y^2+z^2) end proc

(1)

expr := (y-z)*diff(u(x, y, z), x)+(z-x)*diff(u(x, y, z), y)+(x-y)*diff(u(x, y, z), z)

2*(y-z)*(D(f))(x^2+y^2+z^2)*x+2*(z-x)*(D(f))(x^2+y^2+z^2)*y+2*(x-y)*(D(f))(x^2+y^2+z^2)*z

(2)

simplify(%);

0

(3)

u := (x, y, z) -> C*f(x^2+y^2+z^2)*exp(x+y+z)

proc (x, y, z) options operator, arrow; C*f(x^2+y^2+z^2)*exp(x+y+z) end proc

(4)

expr := (y-z)*diff(u(x, y, z), x)+(z-x)*diff(u(x, y, z), y)+(x-y)*diff(u(x, y, z), z)

(y-z)*(2*C*(D(f))(x^2+y^2+z^2)*x*exp(x+y+z)+C*f(x^2+y^2+z^2)*exp(x+y+z))+(z-x)*(2*C*(D(f))(x^2+y^2+z^2)*y*exp(x+y+z)+C*f(x^2+y^2+z^2)*exp(x+y+z))+(x-y)*(2*C*(D(f))(x^2+y^2+z^2)*z*exp(x+y+z)+C*f(x^2+y^2+z^2)*exp(x+y+z))

(5)

simplify(%);

0

(6)

pdsolve((y-z)*diff(U(x, y, z), x)+(z-x)*diff(U(x, y, z), y)+(x-y)*diff(U(x, y, z), z)=0, U(x,y,z),'build')

U(x, y, z) = exp((1/2)*x^2*_C2)*exp(_C1*x)*exp((1/2)*y^2*_C2)*exp(_C1*y)*_C3*_C5*_C4*exp((1/2)*z^2*_C2)*exp(_C1*z)

(7)

combine(rhs(%), exp)

exp((1/2)*x^2*_C2+_C1*x+(1/2)*y^2*_C2+_C1*y+(1/2)*z^2*_C2+_C1*z)*_C3*_C5*_C4

(8)

 


 

Download Problem_19.mw

Hello,

I got problem how to rewrite formula in maple, I have tried so many times but it is not working.

How to rewrite sum of double sum like this formula (4th constraints in the following picture)

H := numelems(N); for k from 2 to H do for i to k-1 do cons[k] := add(x[i, k], i = N)+add(x[k, j], N) = 2 end do end do;
                             H := 5
Error, invalid input: add received {1, 2, 3, 4, 5}, which is not valid for its 2nd argument, i

 


for example, there is an expression exp1=(a+b)*(a+c),  I want to find all the position in DAG of a specific operand, such as 'a' ; also I want to find the position in the DAG of  sub-expression which type is '+' .
 is there any function in maple which can return the  integers indicating position of an operand or type in an expression? i.e. with this function, assume its name is 'find',then
find(exp1, a) will return  [1,1],[2,1];
find(exp1,'+') will return  [1,0],[2,0];

hi

i got a problem to solve 2 nonlinear  pde equation that are not coupled but there is 8 coupled boundary condition. i can use pdsolve in maple.anyone can help me in numerical solving of these pdes?

Hello

How can I set the range (bounds) of all of the function's variables to the same range at once? Here is a simple exaple:

 

Input:

Minimize((x[1]-1)^2+(x[2]-1)^2+(x[3]-1)^2, {8 <= x[1]*(x[2]^2+x[3]^2+1)}, x[1] = 1 .. 2, x[2] = 1 .. 2, x[3] = 1 .. 2);
     

Results:

[0.693290283715211841, [x[1] = 1.53166579937811,  x[2] = 1.45311243719790, x[3] = 1.45311243719790]]
 

My function have 15 variables x[1] -> x[15]. How can I set their bounds to a global range, say: x[i]=1..2 ?

I'm using Maple 17.3 at work.

Thanks, and sorry for the bad English.

 

This is from the documentation of ?plot3d,light:

 

light=[phi, theta, r, g, b]

    This option adds [my emphasis] a directed light source

    from the direction phi, theta in spherical coordinates.

 

The "adds" in that sentence seems to imply that

multiple light sources are possible, but it does not seem

to work that way.  Each subsequent light option overrides

the previous one as we see in the following illustration

where we render a ball three times by illuminating it

(a) from the north, (b) from the south, and (c) from

both the north and south.  In (c) Maple accounts for only

the south light.

restart;

with(plots): with(plottools):

ball := sphere(1, style=surface, color=gold):

display(<
    display(ball,light=[0,0,1,1,1])   |
    display(ball,light=[180,0,1,1,1]) |
    display(ball,light=[0,0,1,1,1], light=[180,0,1,1,1])
 >);

 

Download light.mw

 

When I try:

X≔Statistics[RandomVariable](Normal(0,1)):
Statistics[Sample](X,10);

I get:

Error, (in Statistics:-Sample) invalid input: expected distribution or algebraic expression with random variables, but received X

What am I doing wrong?

Hello,

I am trying to parallelize the output of my Maple18 program, such that it is able to write into multiple smaller output files at the same time, rather than into one unique big file spending much time in this operation...

This is the code:

 

 


 

 

 

As you can see from the code, I have tried with different combinations of options. The errors that I get are:

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

(only one file: "rows-1 < 10000")

Option1A = Error, (in fprintf) string expected for string format

Option1B = Error, (in unspecified) Too many levels of recursion for display

Option2A = OK (but there isn't parallelism here....)

Option2B = OK (but there isn't parallelism here....)

--------

(more than one file: "rows-1 > 10000") 

Option1A = Error, (in fprintf) string expected for string format

Option1B = Error, (in unspecified) Too many levels of recursion for display

Option2A = Error, (in StringTools:-Split) first argument must be a string

Option2B = Error, (in StringTools:-Split) first argument must be a string

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


Instead, if I simplify the definition of D_vol to one single sum (for exemple 2+2), this is what I get:

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

(only one file: "rows-1 < 10000")

Option1A = OK (but there isn't parallelism here, and the example is trivial 2+2=4)

Option1B = OK (but there isn't parallelism here, and the example is trivial 2+2=4)

Option2A = OK (but there isn't parallelism here, and the example is trivial 2+2=4)

Option2B = OK (but there isn't parallelism here, and the example is trivial 2+2=4)

--------

(more than one file: "rows-1 > 10000") 

Option1A = OK (but the example is trivial 2+2=4)

Option1B = OK (but the example is trivial 2+2=4)

Option2A = Error, (in StringTools:-Split) first argument must be a string

Option2B = Error, (in StringTools:-Split) first argument must be a string

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

Can you please help me? Any advice wil be really useful....

Thanks

 

in maple, i can't use print? Help me. Please.

I'm trying to make a Least-Squares curve fitting plot.  I need to sequence two rows from a data file I imported (see attached worksheet GR10_20190130_PSA_TESTS.mw).  More specifically, I need to sequence the data in

X:=Row(T,1) with the data in y:=Row(T,2).  It should look like

([41115.0,6.97],[41257.0,18.9],[41270.0,15.67]...[43495.0,4.06]) when complete.  I tried seq[X_k,Y_k], that didn't work.  Also tried using an index of 1 to 25 (the number of elements in each row), that didn't work.  Any help with this appreciated, thanks in advance!

Les

Hi

For educational needs; I try to animated some statistical concepts with simple statistical commands of Maple on 2018. The WorkSheet  in appendix, gives the desired animations, but with rather heavy procedures. Thanks for your help.

Proc1limitmgf_(1).mw 

Hi !
I made a program that solves a series of system of linear equations of increasing dimension.
Equations with rational numbers. I have a list of equations "liseq1" and a list of variables "lisvar1".
I use the following command :
 
solve(liseq1,lisvar1) ;
 
When the equation system reaches dimension 32, Maple gives me the following error message :
 
"Error, (in LinearAlgebra:-Modular:-IntegerLinearSolve) invalid arguments to iratrecon" .
 
It is an overdetermined system with 33 equations and 32 unknowns .
The variables are defined with the command:
 x: = array (0..31) ;
 
I managed to work around the problem by replacing the variables with the following commands :
 
lissub: = seq (x[i] = x||i, i = 0..31) ;
lisvar2: = subs(lissub, lisvar1) ;
liseq2: = subs(lissub, liseq1) ;
solve (liseq2, lisvar2);
 
If you run the file I sent, Maple sometimes gives the desired answer but in a random way
because if you run the last 3 lines in a different order you will get the answer or the
error message .
 
Something remains in memory. Sorry, but it's a bug.
I have Windows 10, 64 bit with Maple 2018.2.
Regards .

Hello,

I'm a long-time Maple user and have used the CodeGeneration package in the past, but with a recent download of Maple 2018, I'm now getting an error I have never gotten before. Even when I do something simple (see below, for example), I get an error that reads "Error, (in clear) argument `` is incorrect or out of order". And I get this error no matter which language I choose. Any help would be much appreciated.

> with(CodeGeneration)

> R(exp(x))

Thanks!

 

 

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