## How to replace a string by an expression in the ed...

I have many expressions in a worksheet like this:

latex(%, "equations.tex", append = true)

I should have defined a file name like this:

fname := "C:/home/MyStuff/Economics/MICRO NOTES/equations.tex"

And then replaced the first expression throughit the worksheet by:

latex(%, fname, append = true)

To acheive this I open the Find/Replace dialogue as in picture below:

This does not work. Instead of replacing with fname the result is "fname" .  Is there any way of doing what I want?

## how to print matrix like command in text file with...

interface(prettyprint=0):
interface(screenwidth=500):
with(LinearAlgebra):

expect

Matrix([[a1,a2,3],[5,6,7],[9,10,12]])

but

it print datatype = anything,storage = rectangular,order = Fortran_order,shape  and (2,1) etc

Matrix(3,3,{(2, 1) = 1, (3, 1) = 1, (3, 2) = 1},datatype = anything,storage = rectangular,order = Fortran_order,shape = []),

## what are the dynamical system which act on invaria...

what are the dynamical system which act on invariant manifold?

## Using numeric with dsolve and producing a polarplo...

Hi,

Quick question.  If I was to solve a second order ODE using the dsolve function, and I was to use the numeric option such that I get a Procedure as the result.  Lets say I run something like sol:=dsolve(...,numeric);  If theta is the parameter to sol, then I can obviously call sol(Pi) to return the solution at Pi, I will receive the following result [theta=Pi, r(theta)=..., D(r)(theta)=...].

Now, lets say I wanted a Polarplot of [theta,r(theta)], how can I acheive this?

I have tried several ways, my thinking was something like polarplot(rhs(evalf(sol(theta))[2],theta=0..2*Pi); but I get the following "Error, invalid input: rhs received eqn_n(theta)[2], which is not valid for its 1st argument, expr".

Would anyone of you clever people have any pointers on how to polarplot a numeric solution?

Thankyou.

## How do I make a plot for random walk problem?...

Hi!

I'm doing an assignment where we are supposed to create a random walk with 3 options (go straight forward, turn left, turn right), and the first step is to be taken to [1,0]. I am supposed to plot the result afterwards, but when I plot it, it's empty...

(The first # is forward, the second # is to the right, and the third # is to the left)

for i to M0 do

X[i, 0] := 1; Y[i, 0] := 0;

for j from 2 to M1 do

r := R3();

if r = 1 then X[i, j] := 2*X[i-1, j]-X[i-2, j]; Y[i, j] := 2*Y[i-1, j]-Y[i-2, j];

elif r = 2 then X[i, j] := X[i-1, j]+Y[i-1, j]-Y[i-2, j]; Y[i, j] := Y[i-1, j]-X[i-1, j]+X[1-2, j];

else X[i, j] := X[i-1, j]-Y[i-1, j]+Y[i-2, j]; Y[i, j] := Y[i-1, j]+X[i-1, j]-X[i-2, j];

end if;

end do;

end do:

Then, for the plot:

plot([[[([X[i, j], Y[i, j]], \$j = 0 .. M1)], \$i = 1 .. M0)], scaling = CONSTRAINED);

This is what I got for the plot:

Where have I gone wrong?

## Maple and Excel ...

Hello everybody,

I used Maple to reach a function in terms of a few parameters. The issue that I'm facing is that when I copy and paste that equation to excel(after transforming that same equation to 1D math) for evaluating it's value with the real values for the parameters, the result is not the same as the one calculated by Maple 2016 with the exact same parameters. I've inserted the file with this question for further information. One of the parameters (F15) is the cell used in excel.

equation.mw

Any help regarding this problem is very much appreciated.

## How to simplify formula like e^(ln(2*Pi)*n)?...

I have tried

assume(n >= 0, n::integer);

But still,

simplify(exp(-n*ln(2*Pi)))

does nothing.

I want to convert it to (2*Pi)^(-n).

## Where can I send a proposal for an evolution of a ...

Hi,

I am doing Principal Component Analysis (PCA) and I think the Biplot procedure could be improved.

When you use PCA is common to look what happens in other planes than the plane defined by the first two eigenvectors.
Unfortunately Biplot deals only with 2D projections onto this first plane and with 3D projections onto the space spanend but the first three eigenvectors.

I modified slightly the original Biplot procedure for it to handle different 2D and 3D projections planes.
The code is given in the attached mw file (original commands are written red over yellow and the new ones yellof over red).

I'm not at all certain mapleprimes/questions is the best place to post ???

Biplot.mw

## Why plotsetup doesn't work as expected when invoke...

Hi,

This sequence of commands works perfectly well

plotsetup(jpeg, plotoutput=SomeJpegFile);
plot(x, x=0..1);
plotsetup(default);

Why this one doesn't create the file SomeJpegFile ?

f := proc()
plotsetup(jpeg, plotoutput=SomeJpegFile);
plot(x, x=0..1);
plotsetup(default);
end proc;

f();

## What's the problem in this numerical integration b...

Maple gives the integral's face instead of giving a number as the numerical integration, no matter what command for the numerical integration I use. Does any one know what the problem is?

```T2start := -5.036645000*10^9*(x[5]^2+.2725890432*x[5]+.3732640349)*x[5]/(5.036645000*10^9*x[5]^2+1.27004241*10^8*x[5]+5.3714241*10^7);
T2end := -5.036645000*10^9*(x[5]^2+.2871403962*x[5]+.3945934083)*x[5]/(5.036645000*10^9*x[5]^2+1.27004241*10^8*x[5]+5.3714241*10^7);
J := (25183225000000*x[5]^4+(-100732900000000*T[2]+73827142410000)*x[5]^3+(-112645777230000*T[2]+662242877289)*x[5]^2-2398770574578*T[2]*x[5]-393671672289*T[2])/(10000000*x[5]^2+14658000*x[5]);
int(abs(J), [T[2] = T2start .. T2end, x[5] = 0 .. infinity], numeric);```

I also used the following.

`evalf(Int(abs(J), [T[2] = T2start .. T2end, x[5] = 0 .. infinity]));`

The result was same.

Or when I use

`evalf(Int(abs(J), [T[2] = T2start .. T2end, x[5] = 0 .. infinity], method = _MonteCarlo));`

It gives an error saying:

Error, (in evalf/int) invalid arguments

## How do I get an exact number out of this function?...

Wus poppin Jimbos

My function is as follows:

f(x)=(10000/1+30762*0.478^x)+5

I can then type

maximize(f'(x))

And I get the result which is approximately 1845.361367

I then assign at a name e.g. "M"

I then try and execute the command (where I isolate the expression for x)

f'(x)=M

I get the result

x = 14.00001597 - 0.00005369289477 I

Which is super annoying to look at..

Is there any way that I can remove the - 0.00005369289477 I part? And just get the answer (which should be 14)

I have no problem executing

diff(f(x), x) = 1845.361366;
=
"(->)"

x = 13.99997555

However 1845.361367 once again gives me x = 14.00001597 - 0.00005369289477 I

Any help is appreciated <3

## how to search matrix ?...

Is it a complete set ? How to search matrix?

## Can I execute multiple worksheets at the same time...

When I tried to execute one of my opened worksheets, the "execute the entire worksheet button" became unactive for the others. I am pretty sure there was an option to execute multiple worksheets in Maple 14. Did the developers remove that in newer versions?

## How can I graph equation?...

u:=(x,t)->Sum(sin(r*Pi*x/20)*(4/(r^2*Pi^2))*sin(r*pi/2)*cos(r*Pi*t/20),r=1...1000);

plot3d(u(x,t),x=0...10,t=0...1);

When I want to draw the graph, it gives a straight line. But this is a wave equation

## How can I simplify this logarithmic expression?...

I am trying to calculate log[1/3](x)-log[sqrt(3)](x^2)+log[x](9) with log[3](x) = a.
I tried:

restart;
sol := solve(log[3](x) = a, x);
f :=x->log[1/3](x)-log[sqrt(3)](x^2)+log[x](9) ;
simplify(f(sol))

I don't get the answer (2-5a^2)/a.

How can I get that answer?

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