## modify an expression...

Hello people in mapleprimes,

I want to single out omega^epsilon from and modify the rhs of the following expression
to the expression where the  the part without omega^epsilon and  another part of  omega^epsilon
are multiplied.

Y = -L*epsilon^epsilon*(1-epsilon)^(1-epsilon)*(-omega^(-1+epsilon)*k*theta+(1-theta)*omega^epsilon)/(1-epsilon-theta)

I am glad if you teach me this.

taro

## Another engine dispatch i dont understand...

I found this error extremely confusing when using the solve function:

Error, (in Engine:-Dispatch) cannot determine if this expression is true or false: 1000 < 5^(1/2)

## RootOf Error needing to be dispatched to the engin...

Hi, i encountered this, error, and the link to the help page was broken.

Error, (in RootOf) expression independent of _S000100

## How do I display the numeric value for a trig func...

when I enter a trig function as cos(pi/2) I get as a return the same input.  What I would like is the numeric answer displayed. also there are times when I don't want pi in the answer but a numeric value calculated based on pi * whatever.

Thanks

Bill

## Proof of Least Square Equation ...

I am trying to prove the equation of the least square estimator. For example, I have:

X := Matrix(2,3,symbol=p)

Y:= Matrix(2,1,symbol=f)

b:= Matrix(2,1,symbol=n)

or Y=X.b

The known estimation of b results from the minimization of the objective function:

S:=Transpose(X.b-Y).(X.b-Y).

We take the derivative of the above expression and set it equals with zero.

Then the estimator is: b=MatrixInverse(Transpose(X).X).Transpose(X).Y

How can I get this expression using commands οn maple?

My final task is to change the objective function to see the different estimations. For example if I have the below objective function which is the results of estimation as equation:

S:=Transpose(X.b-Y).MatrixInverse(C).(X.b-Y)

where C:=Matrix(2,2,symbol=w)

Ofcorsse I know the answer, but I am not sure for more complicated objective functions.

## modification of an expression...

Hello people in maple primes,

I have an expression,

e1_1:=-gamma*r*theta/(w*beta*(theta-1))

, which I want to put in order as

gamma*r*theta/(w*beta*(1-theta))

Isn't there any ways to do the modification above?

taro

## NonLinearFit - Operator mode...

Hi!

Here below is the code I got problems:

#################################

Dens := proc(v)
local theta, r;
evalf[8](
Int(
Int(
4*r/(1-0.84*cos(theta)^2)^(1/2)*exp(-r*(6.25-5.245*cos(theta)^2)^(1/2))
, theta = 0. .. 2*Pi)
, r = 0. .. v)
) assuming v>=0
end proc;

#
#

FitFinalDens := NonlinearFit(
b*(1+a*u)/u*Dens(u/(1+a*u))
, depth
, veloc
, [u]
, initialvalues = [a = 1.4, b = 0.13]
, parameternames = [a, b]
, output = [leastsquaresfunction, residuals, parametervector]
, parameterranges=[a=1.1..3.0,b=0.02..0.8]
);

#################################

Then, I obtain two sort of errors:

First error message:

Error, (in Statistics:-NonlinearFit) invalid input: no implementation of NonlinearFit matches the arguments in call, 'NonlinearFit(0.13*(1.+1.4*u)*(int(int(4*r/..........

etc...

Second error message:

Error, (in Statistics:-NonlinearFit) complex value encountered

So, really I don't known how to correct the code.

I tried a lot  of things such as using  "value" command,  "Re" command, etc.

Do you have a solution?

Sincerely yours.

Jacqr

## invalid input: LinearAlgebra:-Basis expects its 1s...

invalid input: LinearAlgebra:-Basis expects its 1st argument, V, to be of type {Vector, set(Vector), list(Vector)

A:=<<5,5,5>|<1,2,3>|<-5,1,2>>;
Basis(A);

## how can i solve with ShowSolution...

restart;
with(Student[Calculus1]);
a := Int(exp(cos(x)), y = 0 .. sin(x), x = 0 .. (1/2)*Pi);
ShowSolution(a);
i get error

## Can't solve arctan equation...

Trying to solve:

solve (arctan((2*x^2-1)/(2*x^2+1)) = 0, x);

The answer I get is the original function:

arctan((2*x^2-1)/(2*x^2+1))

This example is from the Maple book by Keck, and he shows the Maple V answer as

1/2 sqrt(2) -1/2 sqrt(2)

Suggestions?

## Solve the PDE with conditions......

Hi every body :

I want to slove this below PDE with conditions 1&2, can every body help me, tnx.

PDE := diff(u(x, t), t)+6*u(x, t)*(diff(u(x, t), x))+diff(u(x, t), x, x, x) = 0;

1.x=0

2.assume t is step function(Heaviside).

with regards....

## How to simplify this solution?...

```restart;
sol:=dsolve(diff(y(x),x)= x/(sqrt(x^2-16))*1/(2*y(x)),y(x));
```

Gives

But the solution can also be written as

I just do not know how to transform the first solution to the second simpler one. I tried:

```sol:=map(x->rhs(x),[sol]);
```

The simpler solution can be found as follows

```restart;
sol:=dsolve(diff(y(x),x)= x/(sqrt(x^2-16))*1/(2*y(x)),y(x),'implicit');
```

But the term in the middle above is

Therefore the solution is really

```eq:=y(x)^2-sqrt(x^2-16)-_C1 = 0;
solve(eq,y(x));```

Which gives

What command to simplify the long solution to the shorter one obtained from the implicit?

## where did the 3 come from? dsolve question....

The solution by Maple below is correct, but non-the-less, a little strange.

```restart;
dsolve(diff(y(x),x)=3*x^2*(y(x)^2+1),y(x));
```

Gives

Ofcourse 3*constant is still constant. But it is a little strange and have no reason for it to be there.  When I solve it by hand

What could made Maple put the 3 in there? Again, solution is 100% correct, but it could be simpler.

Maple 2017.1

## How to animate the rotation of a PLOT3D data struc...

I have Imported a CAD model (.sty) into maple. What I want to do is rotate the model along several axes. At first I want to rotate it around its center. This can be done via

`rotate(Zylinder, 2, 3, 56)`

where Zylinder is the Object I importet via

`Zylinder := Import("C:/...")`

this works fine, but I want the rotation to be a continuous animation. I tried:

`animate(rotate(Zylinder, A, 0, 0), A = 0 .. 360)`

but that does not work. Can you please tell me how to make it work? And it would be great if the aproach would work for rotations around an axis away from the center, too.

## Why am I getting Line-Printed Output instead of a ...

I don't recall ever changing any settings in my copy of Maple 16. But for some reason, I tried to make a plot and it spit out line-printed output rather than a regular plot.

How do I change this back? I have no use for line-printed output.

 Nitrogen Nucleus Second-Order Energy Shifts                    |                                                                              +                                                                     HHHHH 6e-08                                                               HHHHH        +                                                            HHHHHH          4e-08                                                     HHHHHH                 +                                                  HHHHHH                      +                                           HHHHHHH                          2e-08                                  HHHHHHHH                                  +                           HHHHHHHHHH                                         +             HHHHHHHHHHHHHHH                                                  *************************************************************************** 0 +              1    HHHHHHHHHH2HH           3              4              5   +                               HHHHHHHHH                                    -2e-08                                    HHHHHHHH                               +                                              HHHHHHH                       -4e-08                                                 HHHHHH                    +                                                         HHHHHH               +                                                              HHHHH         -6e-08                                                                HHHHH      +                                                                       HHH