## Can I convert a date time string into a form I can...

This is most likely a simple question for the power users of this forum, but I do not manage to find a solution. I have date in an Excel file. The first column consists of dates (mm/dd/yyyy) and the second of time (hh:mm). I can easily concatenate both in Maple using cat("9/7/2023", "10:22") but how can I convert the obtained string into a date+time that Maple understands?

## How to solve a linear system with 7 variables and ...

I create a system of equations (with 9 linear equations and 7 variables).
I get 7 equations from the multiplication of a matrix M with a transposed vector of the 7 variables equals the transposed vector of the 7 variables. Other two simple equations are necessary because they are restrictions. Those two equations a re very simple and thave the 7 variable sin it.
To start I have been trying with fsolve but i haven't been able to solve it yet, as I also get the error: "Error, (in fsolve) number of equations, 9, does not match number of variables, 7"
Have you andy idea to solve this problem? Thanks in advance.

## How to find the value of constants?...

Hi all, any one help  me to find the values of constants by using given condition and then how to varify that the goiven condition varify the expression. I have found manually but want to varify through maple.

help.mw

## How do I write Homotopy Perturbation method for a ...

HPM.mw

• How do I write Homotopy Perturbation method for a partial differential equation for this question in Maple?

## Error using SingularValues in a procedure...

Using the SingularValues command with any output type specified causes this error

Error, (in sanity) invalid input: LinearAlgebra:-SingularValues expects value for keyword parameter output to be of type {list(identical(U,S,Vt,list)), identical(U,S,Vt,list)}, but received [U, S, Vt]

Below is a minimal example to trigger the error. Is there something wrong about how I am calling the function?

restart:
with(LinearAlgebra):

sanity := proc()
local A,U,S,Vt;
A :=RandomMatrix(3,10);
U,S,Vt := SingularValues(A, output=['U','S','Vt']);
end proc:

sanity();

## Newton iteration not converging...

Good day all,

please I am new Maple user, i used the same code to solve boundary layer flow. Itried to use the same code in solving nanofluid but the solution is not coverging at some point. But the author i want to compared my results with had solution at those points.

Is there any way i can get solution of this model at this with these values?. Please i need your help. Thank you in advance

secod_code.mw

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 > for k to 10 do       sol_All := dsolve                  ( eval                    ( {bcs1, ode1, ode2,ode3},                      [xi= L[k],R=1, CT=0.2, Gr=0.5, Gc=0.5, lambda1=0.2, lambda2=0.2, Pr=0.72, Nb=0.5,  Le=1, dc=0.2, de=0.2, Nt=0.5, Zeta=0.5, varsigma=0.5, M=1.5, bet=1.5]                    ),                    [f(eta), theta(eta),phi(eta)],                    numeric,                    output = listprocedure                  );       Y_sol || k := rhs(sol_All[5]);       YP_sol || k := -rhs(sol_All[6]); feta || k := rhs(sol_All[4]);       fpeta || k := rhs(sol_All[3]); phieta || k := rhs(sol_All[8]);       phipeta || k := rhs(sol_All[7])   end do:
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 > plot( [ seq((Y_sol||j)(eta), j = 1..6)],          eta = 0 .. 6,          labels = [eta, theta(eta)],          axes = boxed       ); plot( [ seq((YP_sol||j)(eta), j = 1..6)],          eta = 0 .. 8,          labels = [eta, thetaprime(eta)],          axes = boxed       );  plot( [ seq((feta||j)(eta), j = 1..6)],          eta = 0 .. 8,          labels = [eta, f(eta)],          axes = boxed       );   plot( [ seq((fpeta||j)(eta), j = 1..6)],          eta = 0 .. 5,          labels = [eta, fprime(eta)],          axes = boxed       ); plot( [ seq((phipeta||j)(eta), j = 1..6)],          eta = 0 .. 5,          labels = [eta, phiprime(eta)],          axes = boxed       ); plot( [ seq((phieta||j)(eta), j = 1..6)],          eta = 0 .. 5,          labels = [eta, phi(eta)],          axes = boxed       );

## Why is Maple not calculating 'sqrt' ?...

Why is Maple not calculating 'sqrt' and continuously showing 'Evaluating'?

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Hi.

When trying to open my document it says:

Would you mind helping me?
I saw some scripts on how to fix it, but simply can't solve it myself.

Regards Samuel

Basismat_2_noter.mw

## Cannot map a function with `mod`...

I am slightly confused as I can't apply the seemingly correct function to a sequence. It seems like `modp` does not like my inverse. But I am not aware of any other way of finding the modular inverse.

 > a := i -> (1025 - 2^(10 - 2^i))^(-1) mod (1025 - 2^(10 - 2*2^i));
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 > map(i -> i + 1, {seq(1 .. 4)});
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 > map(i -> 1/(1025 - 2^(10 - 2^i)) mod (1025 - 2^(10 - 2*2^i)), {seq(1 .. 4)});
 > map(a, {seq(1 .. 4)});

## Error, invalid input: rhs received 19715.18184, wh...

Hi, I am completely new to Maple and I keep getting this message:

Error, invalid input: rhs received 19715.18184, which is not valid for its 1st argument, expr

my code is:

sqq:=Vector(n):
for i from 1 by 1 to n do

sqq[i]:=rhs(pom):

end do:

I am trying to get a vector sqq solving the equation sigma[qq] using the constants and vectors written there. Can anybody help me please?

## how I can plot a contour like attached figure...

how I can plot phi[2] as a contour like attached figure?

tez-1.mw

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## Nested Maximization...

Hi,

I am working on an optimization problem, where i want to Maximize numerically a function (it is too complex to have a deriviatve) here a pseudo code:

Maximize(f(x,y,z), initialpoint = {x=1,y=1,z=1},iterationlimit = 9999);

Now i have a constraint on (x,y,z) where I want the maximum of another function be smaller than a threshold. Problem is, that the constraints function does not put it the corresponding x,y,z tupel and therefore the maximization regarding f does not come to a solution.

Maximize(f(x,y,z), {Maximize(g(x,y,z,f),{0<f<1})[1]<Thres},initialpoint = {x=1,y=1,z=1},iterationlimit = 9999);

Maybe you guys have an idea how to solve this.

Best

## Crank–Nicolson Finite difference scheme ...

How to get same graph from maple with finite difference method for differential equations

I m new here how to plot this i have seen related posts no where given clear idea for FDM method

plase help me to get the results Thank you

## Why does this Maple calculation with units differ ...

I am creating a Maple document mode worksheet in which I use the Units package. I was doing a calculation and I noticed a discrepancy when I repeated the calculation slightly more manually (but still expecting the same result).

Here is a link to the worksheet: Units.mw

(Unfortunately, it is hit or miss for me when I try to use the option to show the contents of the worksheet here directly)

Here is a screenshot of the issue

All I am doing in the second calculation is doing some of the unit conversions myself.

I came across this while solving a chemistry problem, and I know the answer in the book agrees with the second calculation.

So the question is why doesn't the first calculation, which uses more of Maple's library to do the calculation, agree with the second calculation?

## Wrong maple output, shows apostroph in the variabl...

Hi,

So I've just installed the 2022 version of Maple and I wanted to make a new document.

But when I'm trying to make a variable with a subscript that includes a comma, I get wrong output.

For example; I want to make the variable Ab,c as 2D input and then it shows 'Ab,c' as output.

Why are those apostrophs showing up?

Thanks for the help

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