Hello

I have some problem with " For loop". If i add more then one expression the, i recieve an error. Could you please help me to solve it? I have attached my file. Thank you.

Download pak2.mw

I have the following mathematical expression

where a=0.2, b=0.09, c=0.57, p=0.3 and q=1-p=0.7, Now i want to find the value of n for which the value of the expression will be 1, i.e., for what value of n , A_n will be 1?

Hej hej,

is there a way to obtain confidence intervals for the parameters in a NonlinearFit? To give you an impression of the problem which I was working on, I created a minimial working example (not sure wheather that actually helps). In this particular case, I have two parameters to fit the coefficients of a binomial series to some data I obtained. Beyond the values of the parameters (in a least square fit), I'm also interested in some kind of confidence interval, to get a feeling about how realiable my values are. Is there a direct (or even indirect) way to obtain such a thing. Either directly as a Maple function (confidenceintervals is not supported for NonlinearFit, if I'm not mistaken) or as something I can implement myself (within a reasonable time frame, as in hours rather than days).
Thanks in advance!

Cheer,

Sören

Download nonlinearfit-problem.mw

I'm trying to use Maple to show that the Hilbert transform of the natural log of |H(jw)| is -arctan(H(jw))

for a minimum phase network; The network I choose is the simplest filter there exists i.e. a low pass RC-filter

with transfer function H(jw)=1/(1+tau*j*omega) therefore |H(jw)|=1/sqrt(1+(tau*omega)^2))

Here is what I did:

assume(omega > 0); assume(tau > 0); interface(showassumed = 0);

result5 := (int((1/2)*log(1+(tau*nu)^2)/(nu-omega), nu = -infinity .. infinity, CauchyPrincipalValue))/Pi

simplify(result5, symbolic)

unfortunately this does not give me the expected result: -arctan(w*tau*omega)

can anyone here tell me what the right way to do it is?

thanks in advance

hugo

I have an equation,

     y = 2x²+7,

Plotting y against x will give a quadratic graph, but plotting y against x² should give a straight line. The problem is I cannot do

  plot([y], x² = -5 .. 5);

It gives me an error

    Error, (in plot) unexpected option: x^2 = -5 .. 5

I have searched online but no links. Can anyone help with this.

Thanks

Fairoz

Dear all,

I have a question regarding the dsolve procedure in Maple. I'm trying to construct a neutron star model using the Tolman-Oppenheimer-Volkoff equation using a polytropic equation of state (EOS) which requires me to solve the ode system:

diff(rho(r),r)=-(rho(r)*(1+K/(5/3-1)*rho(r)^(5/3-1))+K*rho(r)^(5/3))*(4*Pi*r^3*K*rho(r)^(5/3)+m(r))/(K*5/3*rho(r)^(5/3-1)*r*(r-2*m(r)))

diff(m(r),r)=4*Pi*rho(r)*(1+K/(5/3-1)*rho(r)^(5/3-1)

where I have used the EOS P(r)=K*rho(r)^(5/3) and K is a known constant. rho is the density of the star, m it's mass and P the pressure inside the star.

For the initial conditions I have chosen: rho(10^(-10))=rho_0 and m(10^-10)=0. I have chosen r=10^-10 as the innermost point for the integration, since the differential equation for rho is singular at r=0. rho_0 is the central density of the star.

I solve these equations numerically using:

TOV:=dsolve({ode,ics},numeric,output=listprocedure)

where ode is my system of differential equations and ics are my initial conditions. I need now the radius of the star (R_star), which is the maximum value of r, up until which Maple has carried out the integration.

My problem is, I don't know of any efficient way, to do this. What I'm doing currently is defining a procedure TOVr:=rhs(TOV[1]) and I evaluate it at a very high value of r, for which Maple returns me the error message: "Error, (in TOVr) cannot evaluate the solution further right of ..., probably a singularity". I then use the command TOVr('last') to call the maximum value of r and to store it.

I can use the above method, as long as I'm solving the ODEs only for a few different values of rho_0. But I would like to plot m(R_star) for values of rho_0 ranging from 10^(-14) to 10^(-12) in order to find the value of rho_0, for which I can obtain the maximum value for m(R_star). But this requires me to know the value of R_star for every rho_0 and using the above method is not feasible for say hundred different values of rho_0, since I can't write a loop, because it get's terminated as soon as Maple gives me the first error message.

I was thinking of using perhaps the 'events' command in dsolve, to stop the numeric integration once the value for the pressure drops very low, say below 10^(-46), since the radius at which P(r)=0 defines the stellar surface. I tried using:

TOV:=dsolve({ode,ics},numeric, events=[[K*rho(r)^(5/3)-10^(-46),halt]])

but if I try again to evaluate the solution at a large value of r, I get the above error message, and the integration doesn't get canceled, although the value 10^(-46) is bigger than the value for the pressure I would obtain for R_star using TOVr('last') and Maple shouldn't encounter a singularity.

Am I using the 'events' command wrong? And does somebody know of a more efficient method to obtain the maximum value of a variable after carying out a numerical integration using dsolve?

Sorry for the long post and thank you all.

Hello

Is there any option to create a vector with logaritmically spaced? somthing like "logspace" in matlab. (logspace(0:10:20))

Thank you.

Dear Community Members,

We have problem with calculation in Maple v11 and v18. when we make a calculation by using maple v11 and v18, we was not able to get the solution as you see enclosed. when we clicked to "enter + ; ", programme does not run.

For learning, I was trying to implement this in Maple. Given this matrix

m:=<<"foobar"   | 77>,
         <"faabar"   | 81>,
         <"foobaa"  | 22>,
         <"faabaa"  | 8>,
         <"faabian"  |88>,
         <"foobar"  | 27>,
         <"fiijii"      | 52>>;

And list of keys 

keys:={"foo","faa"}:

The idea to find the entries (in first column) which starts with the keys, and sum the corresponding numerical value in the second column. The result will be

r:= <<"foo"|126>,
        <"faa"|177>>

I tried using select, but select, once something is found, does not allow one to do anything more, so it is not very useful. For example  select[flatten](x->x[1..3]="foo",m);  just returns the fields in first column. 

I can extract rows I want like this

f:=x->seq(`if`(m[i,1][1..3]=x,m[i],NULL),i=1..7):
r:=map(f,keys);

Not very useful, but at least I got the parts I want, but still need to process these again.

I could write a loop to do the whole thing, but I am trying to avoid this.

What would be the correct Maple way to do this? I think there might be a command in some package that will do this in one or 2 lines only.

Heyho,

I'm pretty new to Maple (started Monday). And I don't know how to solve (or even why it exists) the following error:

S3() generates two integers, one converted from a random 568-Bit-number "e" and one converted from a random 160-bit number "kp1", satisfying gcd(e,kp1)=1.
That works pretty fine so far.

Now I need two specific numbers, x and y defined by:

And I use the proc S4 to get them:

Sometimes, the error occurs "Error, (in S4) the modular inverse does not exist", and I dont get why,... I tried to fix it, with the "while"-loop, but it didnt work out yet.

Someone knows how to solve this problem?
Thanks!

Hi

how can solve this system of equations:

-dp/dz=(0.855*(1+2*x))/p

dx/dz=((6.39*10^-3*p*(1-x))/(1+2*x))

that x=f(z) and p=f(z)

and at z=0     p=5 bar  & x=0

Dear all

I want to know, how one can install third party package into Maple13, the package is "wkptest" i downloaded it from link http://cpc.cs.qub.ac.uk/summaries/ADTY. If anyone knows how to do this please help.

When I create a component, here a label component, and set a name property and then click OK, that name seems to go into some list never to be erased. If I then delete the first name and put in a new name and click OK. thus saving it, and the then try to use that name again on a different component, I am told that the name is already in use. Well, no existing component has the name, but it is still in Maple's list of components. If I go to edit an action for any component and input %+command completion, I get a list of components which includes the deleted name which does not belong to any existing component. Since the name is on this list, I cannot reuse the component name.

How do I clean up this erroneous list of component names, so that a mistake in naming one component doesn't forever prevent me from using it on the component for which it was intended?

I run the same notebook in Maple 2015 that I used to run in Maple 18.02.

I noticed that it no longer auto-scroll when the print messages reached the bottom of the window as it did with Maple 18.02. This means, I can't see which line the computation is at at the moment, since I can't see the last line printed (it is not visible), without me having to manually use the vertical slider to scroll down trying to catch up with it. But it is hard to do this all the time.  It starts to scroll ok until the last printed message reached the bottom of the window, but then it stops.

This is very annoying, becuase I'd like to see the messages as it is running, so I know which equation is being solved when I look at the screen.  The messages are like this, with some print message I put in the loop

memory used=0.53MiB, alloc change=0 bytes, cpu time=16.00ms, real time=7.00ms, gc time=0ns
*** loop counter 100
etc..

Is there an option one has to configure to make the screen scoll with the output? I looked but do not see one now.

I do not remember having to do anything in Maple 18.02. It seems natural that it should scroll down as messages are being displayed. This is how all apps work.  

I am using Maple 2015, windows 7, 64 bit OS and 64 bit Maple. Using Worksheet, was created in Maple 18.02. Other than this, everything else works ok so far.

interface(version);
Standard Worksheet Interface, Maple 2015.0, Windows 7, February 17 2015 Build ID 1022128

thank you

Hello every one,

I am trying to solve a backward induction problem (game theoretic problem) in maple. Lets say we have S rounds. I start from bottom (S-th round) and solve a parametric equation. Then I put the solution in the upper level (S-1). Then, update the functions at level and solve the equation pertatining to this level (S-1). Again, I put the solution ofround S-1 into the equations of S-2 and update the equations and parametrically solve the equation belonging to level S-2 . This process repeats till the first level.

The issue is that the solution gradually becomes larger and larger. I guess that's why Maple is not able to solve it. 

Have any of you guys faced to a similar problem. Any suggestion?

I was thinking of asking maple to reduce its precision in computations. I mean there may not be necessary to store a number with 100 digits precision! However, I don't know how to do that (I don't know the command). Any suggestion?

Thank you in advance.

Ahmadreza