## 395 Reputation

7 years, 192 days

## How to recover only the contents of m-fi...

Maple 2017

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

## How to solve or reduce a set of nonlinea...

Maple 2018

Hello

I need to solve or reduce (similar to the command Reduce in Mathematica) sets of nonlinear equations.  One such example is shown below:

`eqns := {-1+theta[3, 6] = 0, 1-theta[3, 6] = 0, alpha+rho-theta[2, 2]+theta[3, 3] = 0, -theta[3, 6]^2+1 = 0, theta[2, 2]*theta[3, 6]-alpha = 0, theta[2, 2]*theta[3, 6]^2-alpha = 0, -2*theta[3, 3]*theta[3, 6]-2*rho = 0, theta[1, 2]*theta[2, 1]*theta[3, 6]^2+1 = 0, -alpha^2+rho^2+theta[2, 2]^2-theta[3, 3]^2 = 0, -theta[2, 2]^2*theta[3, 6]+2*theta[2, 2]*theta[3, 3]*theta[3, 6]+alpha^2+2*alpha*rho = 0, -theta[1, 3]*theta[2, 2]^2*theta[3, 0]+theta[1, 3]*theta[2, 2]*theta[3, 0]*theta[3, 3]-alpha^2*beta-alpha*beta*rho = 0, -theta[1, 2]*theta[2, 1]*theta[2, 2]*theta[3, 6]+2*theta[1, 2]*theta[2, 1]*theta[3, 3]*theta[3, 6]-alpha-2*rho = 0, -theta[1, 2]*theta[2, 1]*theta[2, 2]*theta[3, 3]+theta[1, 2]*theta[2, 1]*theta[3, 3]^2+theta[1, 3]*theta[2, 2]*theta[3, 0]*theta[3, 6]+alpha*beta+alpha*rho+rho^2 = 0, -alpha^2*rho-alpha*rho^2+theta[1, 2]*theta[2, 1]*theta[2, 2]-theta[1, 2]*theta[2, 1]*theta[3, 3]+theta[1, 3]*theta[3, 0]*theta[3, 6]-theta[2, 2]^2*theta[3, 3]+theta[2, 2]*theta[3, 3]^2+alpha+beta+rho = 0}`

and the indeterminates are:

`fc := {theta[1, 2], theta[1, 3], theta[2, 1], theta[2, 2], theta[3, 0], theta[3, 3], theta[3, 6]}`

Since I do know the solution, I issued the following command to check for typos.

```seq(subs(theta[1,2]=-1,theta[1,3]=-1,theta[2,1]=1,theta[2,2]=alpha,theta[3,0]=beta,theta[3,3]=-rho,theta[3,6]=1,eqns[i]),i=1..nops(eqns))
```

and the outcome is zero for all equations.

When I try the command solve as follows:

`solve(eqns,fc);`

the result is

`{theta[1, 2] = theta[1, 2], theta[1, 3] = theta[1, 3], theta[2, 1] = -1/theta[1, 2], theta[2, 2] = alpha, theta[3, 0] = -beta/theta[1, 3], theta[3, 3] = -rho, theta[3, 6] = 1}`

that should be right but it is not what I am expecting.

How can maple return the solution needed?

Some sets of solutions do not have a solution as the one above.  Some indeterminates cannot be found, is there a way maple returns the solution of the ones that can be solved and reduced the set of equations into two parts, solved ones e non solved ones?  I can provide an example if needed.

Many thanks.

Ed

## How to save modules as package...

Hello

I have a couple of functions wrapped into a module and want to make them available as a package.  The two modules have been saved as a mpl file.   I read and tried to follow the instructions on the online help (11. Writing packages) but even copying line by line of commands there, they simply did not work at all.

Problems:

1) After following the instructions on how to add a home dir into libname and saved it .mapleinit (I guess) I issued the commands

`restart; libname;`

my lib path is not there anymore.

.mapleinit shows

libname := "mylibdir", libname:

libname:="/Users/eduardo/maple/toolbox/personal/lib", libname:

2) After issuing savelib, I did

`LibraryTools:-ShowContents(libname[1]);`

that returns [];

Could you send me a set of commands showing how to do it, please?

Many thanks

Ed

PS.  My next step is to write help files for each one of the functions.

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

Maple 2017

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 equation...

Maple 2017

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

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