## How do i retrieve the expression from a "Fit" comm...

How do i retrieve the expression fra a "Fit" command so that i can use the expression for later calculations.

As you can see from the picture below, i use the "Fit" command to find an expression based on the values specified in X and Y. From there i would like to use the expression to find points on the line and to automate the proces. I can succesfully retrieve the expression by using the reference label, but is there another way to retrieve the expression so that i can avoid having to display the expression after evaluating?

I guess the question can be rephrased to: How do i retrieve the same information as the label reference does, but with a command and without using a label reference?

## derivative from finite difference...

Since (1/h)[f(i+1,t)-f(i,t)]=f(x,t)_{x} as h goes to zero, 'i' is the discrete index along x-axis. How to do it in Maple? How to reduce Eq. (5) into continuous derivatives?

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## Why does this error appear after simplifying?...

 > restart
 > V := m^4*(1-(varphi/mu)^p);
 (1)
 > V1 := diff(V, varphi);
 (2)
 > V2 := diff(V1, varphi);
 (3)
 > f := Zeta * (varphi^2);
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 > f1 := diff(f, varphi);
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 > f2 := diff(f1, varphi);
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 > R:= simplify(((V/3-f1*V1/(3*V))/((1-kappa^2*f)/(12*kappa^2)+f1/V)));
 (7)
 > N:=evalf(int((3*V1*kappa^2*((2*V*V1)/3 - f1^2*V1*R/(3*V) - f1*V1^2/(3*V))/(V*(-f*kappa^2 + 1)*(-R*f1 - 2*V1))),varphi=varphi__hc..varphi__end)assuming varphi__hc > 0, varphi__hc > varphi__end);
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## URGENT! How to fix corrupt maple document file ...

Exercises_all_lectures_1.mw

Hello,

I have a Maple document that contains a lot of notes that I have an exam for tomorrow. I opened the document today and it suggests I save a copy of a corrupt document and also it gives me the message "There were problems during the loading process.

Any suggestions for how I could fix this would be greatly greatly appreciated.

Thank you

## how to find CharacteristicPolynomiall of matrix wi...

how to find CharacteristicPolynomiall of matrix with vector entries?

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## Residue for a function...

Since C2=D1.D1inv should be equal to I. But return is just an expression (see attached). Further, how to obtain residue for a function C2?

residue.mw

## How to analyze my polynomial solution?...

I am solving 3 nonlinear equations for 3 variables: lambda_1, lambda_2, and lambda_3. I would expect these lambdas to be real and positive.

Instead of solving my original equations, which are convoluted and not in polynomial form, I try to solve for their numerators first (since their numerators are polynomials). Broadly speaking, such solutions should also solve the original non-polynomial system. More specifically, the solutions thus obtained may be a nontrivial superset of the solutions of the original system. They need to be verified, which should be a much much easier process than obtaining that superset. In the case at hand, my original system is rational functions, and thus the only thing that really needs to be verified is that the solutions do not make any of the original denominators zero.

1st question: How to actually implement such verification? In other words, how to verify that the polynomial solution that I obtain also solves the original non-polynomial system?

2nd question: As you can see from my attached script, I obtain one polynomial solution. How to analyze it? What can I say about its roots? In case there are an infinite number of roots, how can I pin down a closed-form, real, and positive expression of lambda_1, lambda_2, lambda_3 in terms of the four parameters gamma, p, sigma_e and sigma_v?*

*Please note that in SolveTools:-PolynomialSystem I set backsubstitute=false to favour compactness and computational efficiency (which means that I need to do the backsubstitution myself now - how to do it?).

**Perhaps is useful to know that gamma, sigma_e and sigma_v are all real and positive and that p is a real, positive number between 0 and 1 (it represents a probability).

Thanks a lot!

## Error in system of Pdes equations ...

Dear Maple   help me to  to plot the graph please see and rectify.  thanks in advance

i am attaching the codes

inf:=5:
pdes:= R(X,R,t)*diff(U(X,R,t),X)+U(X,R,t)*diff(R(X,R,t),X)+R(X,R,t)*diff(V(X,R,t),R)+V(X,R,t),
diff(U(X,R,t),t)+U(X,R,t)*diff(U(X,R,t),X)+V(X,R,t)*diff(U(X,R,t),R)=Gr*T(X,R,t)+Gc*C(X,R,t)+(1/R(X,R,t))*diff(R*diff(U(X,R,t),R),R),
diff(T(X,R,t),t)+U(X,R,t)*diff(T(X,R,t),X)+V(X,R,t)*diff(T(X,R,t),R)+(1/(Pr*R(X,R,t)))*diff(R*diff(T(X,R,t),R),R),diff(C(X,R,t),t)+U* diff(C(X,R,t),X)+V(X,R,t)*diff(C(X,R,t),R)+(1/(Sc*R(X,R,t)))*diff(R*diff(C(X,R,t),R),R):
conds:= U(X,R,0)=0, V(X,R,0)=0, T(X,R,0)=0,  C(X,R,0)=0,
U(X,1,t)=1, V(X,1,t)=0, T(X,1,t)=1,  C(X,1,t)=1,                                                                          U(0,R,t)=0, T(0,R,t)=0, C(0,R,t)=0,
U(X,int,t)=0,T(X,int,t)=0,C(X,int,t)=0:
pars:= { Gr=5, Gc=10,Sc=2.0}

pars := {Gc = 10, Gr = 5, Sc = 2.0}

PrVals:=[0.71, 1.00, 1.25, 2.00]:
colors:=[red, green, blue, black]:
for j from 1 to numelems(PrVals) do
pars1:=`union`( pars, {Pr=PrVals[j]}):
pdSol:= pdsolve( eval([pdes], pars1),
eval([conds], pars1),
numeric
);
plt[j]:=pdSol:-plot( U(X,R,t),X=1, t=2, R=0..inf, numpoints=200, color=colors[j]);
od:
plots:-display( [seq(plt[j], j=1..numelems(PrVals))]);

## how I can find the solution of differential equati...

how I can find the solution of differential equations with dsolve?

Thesis_(1).mw

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## Solve() with assumptions ...

I have a linear system of 3 equations in 3 variables and have no issues with solving it using solve().

I am having issues with solving it by imposing assumptions on my parameters. The infolevel[solve] now outputs "Entering solver with 6 equations in 3 variables", so I am likely making mistakes in the syntax solve(Eqs, Vars, UseAssumptions) assuming ... first of all, do I even need to do this given the assume statements that I set up on top of my script? How do I make sure that all the assumptions are preserved throughout all the calculations in my worksheet?

Moreover, I don't know why I get SolutionsLost: setting solutions lost flag.

My script: 061123_solving_with_assumptions.mw

## How I put three coordinat in the graph and make ...

How I put three coordinat node in a graph and capture it. I want to display the coordinat node for the same time with the red grapf for the blue and green graph.

garfik solusi fungsi AIS titik kritis 8

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