## Classic worksheet....

Maple Help points out

All Programs>Maple 2017>Classic Worksheet Maple 2017

link that I do not have. Is there a reason for this and how do I fix this?

## How to make Maple to integrate term by term?...

Hello

I wonder how integrate can be applied term by term to the following nonlinear differential equation

`(diff(y(t), t))*(diff(y(t), t, t, t))-(diff(y(t), t))*y(t)^2-(diff(y(t), t))*(diff(y(t), t, t))-(diff(y(t), t))*A*y(t)`

The expected output will be something like

`(diff(y(t), t))*(diff(y(t), t, t))-(1/3)*y(t)^3-(1/2)*A*y(t)^2-(1/2)*(diff(y(t), t))^2+C+int((diff(y(s), s, s))^2, s = 0 .. t)`
`map(x-> integrate(x,t),(diff(y(t), t))*(diff(y(t), t, t, t))-(diff(y(t), t))*y(t)^2-(diff(y(t), t))*(diff(y(t), t, t))-(diff(y(t), t))*A*y(t))`

solves most of it but not the first part.

Many thanks

Ed

## How to recover only the contents of m-files? ...

Hello

I know that anames( 'user' ) recovers the contents of the workspace but I wonder whether it would be possible to recover only the contents of each m-file read within a worksheet.

Many thanks

Ed

## What is the possible reason that cause error in ds...

What is the problem with the initialconsiditions that caused this error?

"Error, (in dsolve/numeric/DAE/initial) missing initial conditions for the following: {Integer}"

Thanks.

## Problem in Solving a first-order linear differenti...

Hello,

I have a problem in solving a differential equation in maple. I got an error which is "unexpected occurence of the variables..." .  I have uploaded my full problem as a pdf and maple worksheet (mw) files.

Untitled_(4).pdf

Prob.mw

## Why does this integral give undefined?...

In the attached maple worksheet integral.mw, I am trying to compute an integral involving hyperbolic cosines. While not straightforward to compute, it should be completely well behaved at zero and both infinities as long as rho is real:

Much to my surprise, maple gives "undefined" as the answer, even if I attach an "assuming rho > 0" to make completely sure that the denominator never vanishes.

If I fix rho to 1 (or any other value) and compute the integral numerically, maple happily gives a numeric value. Moreover, I can scale the R, use the fact that the integrand is an even function of R, factor the denominator, and use partial fraction decomposition to transform it into the equivalent form

which maple integrates happily and gives a completely well-defined function in terms of polylogarithms, which agrees with the numeric answer.

Now, I am not expecting maple to just solve every integral I throw at it, but why does it give "undefined" as the answer to a completely well-defined integral?

## GRTensor III problem with defining tensors with co...

Hi.

Im working with GRtensor iii package for Maple.

The goal is to obtain values of specific product of the Ricci tensor and scalar function in FRW spacetime together with second order covariant derivative acting on this product. .

After i defined general 2 covariant derivatives acting on that product

I have errors when i want to define contracted forms of this expression/tensor:

which should be scalar quantity (fY*Rab );ab

and this should have only 2 lower indices ac

Hovewer i obtain errors for both cases
`Error, (in grtensor:-grdef) lhs/rhs index conflict.`

grtensor_v2.mw

## I get the error message: 'There were problems furi...

I get the error message: 'There were problems furin the loading process. Your worksheet may be incomplete.'

The file appears empty. Please, can I get a help to recover the file.

Calculation1.mw

## How to compute a recursive sequence...

How is it possible in Maple to keep hold of pre determined results for comparison with subsequent results so that a recursive decision can be made to either modify the list of “kept” data or to continue to the next calculation, etc... ?

Example: a simple “subtract or double” sequence. If subtracting (say 1) from the current number would result in a term we already have,  then double it instead, and start over again with subtraction.

Formally: a(0)=0, a(1)=1, and for n>=1,

a(n+1) = a(n)-1 if that number has not been found already, else a(n+1)=2*a(n).

0,1,2,4,3,6,5,10,9,8,7,14,13,12,11,22.....

The arithmetic operations are facile but how to organise the keeping and comparison process??

David.

## Maple on chromebooks...

I have managed to install Maple2017 and open the installer using the Linux terminal and everything else but I can't find the file to run maple anywhere. I have been opening and doing everything with the linux terminal but I can't open maple without the filename as chromebook are fairly useless for downloading anything, does anyone know the name of the file or a way to make it run on chromebook? Thanks for any help offered in advance

## How to solve a prime problem...

Take any odd number k, with distinct odd prime divisors p_1,...p_k and ask the following question: What is the smallest even number which when added to each prime divisor p_i of k, gives another prime? Example: k= 119=7*17, so the smallest even number is 6 because 7+6=11 and 17+6=23. NB: some numbers (eg 105,195,231...) seem to have no solution. I would appreciate assistance with a code to calculate for every odd k, the even number in question, or to allocate 0 for numbers where no solution has been found up to some suitably convincing high number like N= 10^5 or 10^6, (a parameter I could change if desired). The idea would be to conjecture that the apparently no solution numbers (up to N) don’t actually have a solution. Any assistance much appreciated in advance. I have found the solutions up to k=781 by hand, but my hand is getting tired now.

cheers,

David.

ps: I would like to have the option (if possible) to output the numbers with solution =  0, and the numbers which are the smallest to have solution 2*n, as separate sequences, for n up to some arbitrary value (ie 3,7,23,69,93...). (n>=1). Hope this is not asking too much.

## How to create variables from a list of variables?...

Hello

I need to create a list of variables from a list of variables.  I thought of something like the code snippet below but I could not figure out how to force Maple to evaluate the variable before creating the new variables.  It is very likely that my approach is completely wrong and I have to use something altogether different.

```vars:=[x,y,z];
for invars in vars do
[invars||(1..nops(vars))];
end do;```

Many thanks

Ed

## How to build a system of linear equations from a l...

Hello

I need to build a system of linear equations from a list of polynomials.  The list of indeterminates is as follows:

`incog:=[theta[1, 1], theta[1, 2], theta[2, 1], theta[2, 2], theta[2, 6], theta[3, 0], theta[3, 3], theta[3, 4], theta[3, 5]];`

The list of polynomials is:

`eq:=[1, theta[1, 1]+theta[2, 2]+theta[3, 3], -theta[1, 1]-theta[2, 2], theta[2, 6]*theta[3, 5], -theta[1, 1]*theta[3, 3]-theta[2, 2]*theta[3, 3], -theta[1, 1]*theta[2, 6]*theta[3, 5]+theta[1, 2]*theta[2, 6]*theta[3, 4], theta[1, 1]*theta[2, 2]*theta[3, 3]-theta[1, 2]*theta[2, 1]*theta[3, 3]+theta[1, 2]*theta[2, 6]*theta[3, 0]];`

eq[1], eq[2] and eq[5] will be used as examples, although all of them should be used.

In eq[1], there are no indeterminates, therefore the first line of the matrix related to the system of equations is:

[0, 0, 0, 0, 0, 0, 0, 0, 0]

In eq[2], there is a summation of  three indeterminates and the outcome is a set of three lines (summation of indeterminates)

[1, 0, 0, 0, 0, 0, 0, 0, 0]

[0, 0, 0, 1, 0, 0, 0, 0, 0]

[0, 0, 0, 0, 0, 0, 1, 0, 0]

In eq[5], there is a summation of a product of indeterminates and outcome is a set of two lines as follows:

[1, 0, 0, 0, 0, 0, 1, 0, 0]

[0, 0, 0, 1, 0, 0, 1, 0, 0]

Carrying on like this will result in a matrix of 14 lines with zeros and ones in positions related to the indeterminates.  Building the matrix is what matters to me.

I have a thousand of such problems with different indeterminates and set of polynomials.

Any ideas on how to build a function to automatically create the matrices would be most appreciated.

Thank you.

Cheers

Ed