## MaplePrimes Questions

In Discontinuous Galerkin Method and Finite Volume Method, 1d and 2d Rieman solver must be employed to get the flux between the adjcent elements.Does maple have the function to solve such Rieman problems? Thanks for ur reply!

## Want to solve equation, need help interpreting res...

I'll start off by saying that I suck at rearranging equations and doing complex maths... which is why I use Maple :) (I've got an old copy of Maple 8, which I use rather infrequently since it's not often I need to calculate complex equations). Right now, I have the equations below: S1 := ((R+(D1*sin(90-x)))^2+(D1*cos(90-x))^2)^(1/2); S2 := ((R-(D2*cos(x)))^2+(D2*sin(x))^2)^(1/2); eqn := (L1/(k*(S1^2)) + L2/(k*(S2^2)))^(1/4) = T; I need to make R the subject of the last equation (R is contained in S1 and S2). To do this I'm assuming that I just need to type "solve (eqn, {R});" to make R the subject but if I do that, I get this:

## HELP!!!!!...

I need some help guys!! I solved 3 simultaneous ODE's using dsolve, and everything went well. But how do I access the variables after? Like if you solve an ODE with dsolve, let's say y'(x) = x after dsolve solve's it, how do you then use y or x? Thanks!!!

## cos(Pi/17) in terms of exact radicals...

How can I find the exact solution? > a20:=cos(Pi/17) = sqrt(sqrt(38*sqrt(17) + 170) + 3*sqrt(17) + 17)/8 + sqrt(34 - 2*sqrt(17))/16 - sqrt(17)/16 + 1/16: > evalf(a20); 0.9829730997 = 0.9829730994 I found cos(Pi/5) and cos(Pi/15). a1:=cos(Pi - 2*Pi/5) = cos(3*Pi/5): > a2:=cos(Pi - 2*x) = cos(3*x); a2 := -cos(2 x) = cos(3 x) > a3:=expand(a2); 2 3 a3 := -2 cos(x) + 1 = 4 cos(x) - 3 cos(x) > a4:=subs(cos(x)=y,a3); 2 3 a4 := -2 y + 1 = 4 y - 3 y > a5:=[solve(a4,y)]; 1/2 1/2 5 5 a5 := [-1, ---- + 1/4, 1/4 - ----] 4 4 > a6:=cos(Pi/5)=a5[2]; a6 := cos(1/5*Pi) = 1/4*5^(1/2)+1/4 > evalf(a6); 0.8090169943 = 0.8090169942 > a7:=cos(Pi/3-2*Pi/5)=cos(Pi/15): > a8:=cos(Pi/3-2*x)=cos(Pi/15): > a9:=expand(a8); a9 := cos(x)^2-1/2+3^(1/2)*sin(x)*cos(x) = cos(1/15*Pi) > a10:=subs(sin(x)=sqrt(1-cos(x)^2),a9); a10 := cos(x)^2-1/2+3^(1/2)*(1-cos(x)^2)^(1/2)*cos(x) = cos(1/15*Pi) > a11:=subs(cos(x)=a5[2],a10): > a12:=simplify(expand(a11)); a12 := -1/8+1/8*5^(1/2)+1/16*3^(1/2)*(10-2*5^(1/2))^(1/2)*5^(1/2)+1/16*3^(1/2)*(10-2*5^(1/2))^(1/2) = cos(1/15*Pi) > evalf(a12); 0.9781476005 = 0.9781476007 I have a simplier version. > a13:=sqrt(6*sqrt(5) + 30)/8 + sqrt(5)/8 - 1/8 = cos(Pi/15): > evalf(a13); 0.9781476010 = 0.9781476007

## About Green Equation and Gauss...

I am new to maple. At present, i am do some study on FEM. so i want to ask if there is some command in maple about the fomulation of Green and Gauss theorem. for i want to change to the body integral to the boundary integral. Thanks for your reply!

## Is this a bug in Matlab code generation?...

Seems that Maple outputs ".." instead of ":" for Matlab code. Note that I'm using Matlab 6.5, so not sure if version has anything to do with it. Is this a bug? Any help would be greatly appreciated. Thanks. >Matlab Code generated from Maple follows

## Parse Comma-Separated Text File...

I have a bit of programming experience but am completely new to Maple (using Maple V release 5, by the way). How would a person go about writing a short program that opens a plain text file, and builds a family of sets based on the content. some of these families will be quite large, so we would like to enter the data into the text files not as sets formatted {a,b,c...} but with an uninterupted sequence of characters (interuption can be comma, space or line break) representing the members of the sets, ie. a text file containing abc,def,ghi jkl would create a set equal to { {a,b,c}, {d,e,f}, {g,h,i}, {j,k,l} }.

## make plot parameter edits stay after save and relo...

I am in document mode where I have plots that I generated using the right click on the expression. Then I edit the range and style and drag in two other expressions that plot. everything looks wonderfull until I save and reload the document. and all the edits and dragged in plots are gone. When I try to use plotbuilder to get around this when I reload the document the plotbuilder screens come up when the document executes waiting for all the plot info to be input again. I Think that if I use a worksheet plot command directly with all the parameters and expressions included that it would do what I want. But I would think that when you hit save in document mode it should save what you see.

## Physical size of a plot...

How do I change the size of a plot programmatically from the default size? I can do it by clicking the plot and pulling the borders with the mouse, but not programmatically. When using an embedded plot, one can easily define the the size of the plot component in the x- and y-direction (pixelheight, pixelwidth) using SetProperty from the DocumentTools package. I would like to do the same thing for a regular Maple plot, but have been unable to find the right command. Is it possible to do that? Thank you for the help. Peter

## Error, (in pdsolve/numeric) unable to handle ellip...

1. I have a third order PDE with boundary conditions. I try and solve numerically but Maple 9 returns the above error ... Error, (in pdsolve/numeric) unable to handle elliptic PDEs. Would anyone be able to help? 2. If I transform this PDE into an ODE, it returns that there is a "removable singularity at x=0". How do I solve knowing this? Many thanks for any help. Sandra

## How important are calculators?...

Of those of you who use calculators in your daily lives, how many use algebraic and how many use RPN? Do you care which you use, i.e., do you choose algebraic over RPN or vice versa, or is it simply a case of what you grew up with or what an employer expects/requires? Are you in industry or education? Do you imagine that there would be a value to having Maple run on a hendheld device, one with a decent interface and good graphical display? Rich

## Having problem with infinite series...

I tried Maple to find a closed-form expression of the following infinite
series:
F:=sum(r^j/(1-a*z^j),j=1..infinity)
where r and a are probabilities and |z|<1.
It did not work
Then I tried to get a series expansion of F around z=0, i.e:
G:=series(F,z=0);
Got the following error message:
Error, (in series/exp) unable to compute series
However when the upper limit of the summation is changed from infinity to any pre-defined number;
ex: F:=sum(r^j/(1-a*z^j),j=1..100)
Maple was able to derive the series expansion around z=0.
Is there any way to get the series expansion at z=0, when the upper limit of the summation is infinity ?