Hi MaplePrimers,

I'm trying to solve a system of algebraic equations using 'solve' [float].  I'd prefer to use 'solve' over 'fsolve', as 'solve' solves my system in about 0.05s, whereas fsolve takes about 5 seconds.  I need to solve the system repeatedly at a different points, so time is important.  I don't know why there is such a large difference in time ... 

I have a few piecewise functions of order 3 to 5.  It solves fine with the other (piecewise) equations, but adding one piecewise function which gives me an error while trying to solve:

Error, (in RootOf) _Z occurs but is not the dependent variable.

I think this is due to solve finding multiple solutions.  Is there a way to limit solve to only real solutions?

Thanks in advance!

my_sol.mw

Leonhard is playing a casino game. He places his bet and then rolls a
pair of dice: if the dice sum to 7, 8 or 9 then Leonhard wins the amount of his
bet, and otherwise Leonhard loses his money. Leonhard begins with $100 and
decides to bet $50 at time, until he has either won $100 or has gone broke. What
are the chances that Leonhard leaves the casino a winner?

My soln doesn't agree with the stated answer..25/74

Has anyone else seen the following behavior in Maple 16 and/or 17? In worksheet mode, with 2-D math notation, after hitting <enter> to execute a line several times, the software switches, without warning and unrepeatably, to a mode where only the arrows work -and that is to scroll the sheet. This means the <enter> command is no longer recognized.

My only solution has been to click on the line with the mouse, for which it returns to input mode. This behavior started in version 16 and I switched back to 15. However, I prefer features of 17 such as the different subscript options, that I would like to stay in 17.

I note this behavior occurs on both my Windows based machines and have seen it on students' Mac based machines. We use a common site licence at our institution and I wonder if that might be the problem.

In short - it is a pain.

(Yes, I did try to look for other posters with a similar problem, but failed. )

"Error, (in CheapestPaths) too many levels of recursion"

I received this message after trying to execute Zeilberg's GetMicrosoftJob program found here: http://www.math.rutgers.edu/~zeilberg/tokhniot/GetMicrosoftJob but don't know the cause. Any ideas?

I have following expression:

y1:=t->1/(4*cosh(t)^2)

I:=int(y1(t)^2,t=-T/2..T/2)

Now I tried:

MultiSeries:-asympt(I,T,5)

for which I only get the highest order.

Can I increase the order in any way?

Dear people in this board.

I couldn't solve the following equation.

restart;

solve(gamma*(sigma/(sigma-1))=1,gamma);

On the other hand, I could solve

solve(alpha*(sigma/(sigma-1))=1,alpha);

Error message was 

Error, (in solve) a constant is invalid as a variable, gamma

Why does this sort of things happen?

I hope that you will tell me about this.

Tahnk you in advance.

taro 

Hi

I  have a system of second order differential equation to be solved numerically. I would like to set up events to halt integration  to find the values of phi when r(phi)=2/3 . Here is my code

DE:=diff(1/r(phi),phi,phi)+(1/r(phi))=(G*M/h^2)+(3*G*M/c^2*r(phi)^2));

ics:=r(0)=2/3,D(r)(0)=0;G:=1;M:=1;h:=1;c:=1;

p:=dsolve({DE,ics},numeric,events=[[r(phi),r(phi),halt]],[diff(r(phi),phi)=0,halt]]);

The code only works for the second event so it halts for r(phi)=1.63... etc

How do i stop this?

Thanks for any help.

I have a list of the structure like

['true', ['true','false'], ['true',['false','true'],'false'],...]

Is it possible to complete 'and' operation with all elements of list without knowing exact structure of list?

I have to make a plot for experimental data where x corresponds to time and y is the concentration. So I loaded the values in two lists, ran fit to least squares and got the best fitting curve (it's linear). However, the line has to start at (0,0). How can I Maple to do that for me?

hi, I have tried to run this program unfortunately the program give some errors.

anneal < -function(fun, N, rho, t, theta)

{y=NULL  

theta.old=theta repea {  

s=0  for k from 1 to N  

{

f.old=fun(theta.old)

 theta.new=runif(1,-1,1)+theta.old

 f.new=fun(theta.new)  

if(f.new<f.old){

 theta.star=theta.new  

s=s+1

}

 else  

{

u=runif(1)

 b=(u<=exp(-(f.new-f.old)/(t)))

 theta.star=theta.new*b+theta.old*(1-b)

 s=s+b  

}  

theta.old=theta.star

 y=c(y,theta.star)  

}  

write(y,file="anneal.result",ncol=1,append=T)

y=NULL

 if(s==0)break

 t=rho*t  

if(t<0.1)break  }

 return(y)  

}

cauchy.1=function(alpha){x=c(-4.20,-2.85,-2.30,-1.02,0.70,0.98,2.72,3.50)  return(sum(log(0.01+(x-alpha)^(2))))}

x=seq(-6,6,,300)

y=sapply(as.list(x),cauchy.1)

plot(x, y, type = "1", ylab = "cauchy.1(beta=.1,alpha)", xlab = "alpha")

anneal.result=anneal(cauchy.1,300,.95,10,4)

plot(x, y, type = "1", ylab = "cauchy.1(beta=.1,alpha)", xlab = "alpha")

anneal.result=anneal(cauchy.1,300,.95,10,4)

x = scan("anneal.result")

plot(1:length(x),x,type="1"

can anyone help me on this? can i do something about it

Many thanks.

Hi everyone,

I have been  trying to solve a coupled system of 2 differencial equations, 1 PDEs with 1 ODE.

The code is below.

> restart;

> with(linalg):with(plots):
> PDE:=[diff(x(z,t),t)=(a/Pe)*diff(x(z,t),z$2)-a*diff(x(z,t),z)-(1-epsilon)/epsilon*3*Bi*(x(z,t)-1)/(1-Bi*(1-1/ksi(z,t)))]:
> a=2:Pe=3:Bi=5:epsilon=0.85:

> ODE := [diff(ksi(z,t),t) = (b*Bi*x(z,t)-1)/ksi(z,t)^2/(1-Bi*(1-1/ksi(z,t)))]:
> IC1:=c(z,0)=0:
> IC2:=ksi(z,0)=1:
> bc2:=diff(x(z,t),z):
> bc1:=x(z,t)-1/pe*diff(x(z,t),z):
> N:=10:
> L:=1:
> dyduf:=1/2*(-x[2](t)-3*x[0](t)+4*x[1](t))/h:
> dydub:=1/2*(-x[N-1](t)+3*x[N+1](t)+4*x[N](t))/h:
> dydu:=1/2/h*(x[m+1](t)-x[m-1](t)):
> d2ydu2:=1/h^2*(x[m-1](t)-2*x[m](t)+x[m+1](t)):
> bc1:=subs(diff(x(z,t),z)=dyduf,x(z,t)=x[0](t),z=1,bc1):
> bc2:=subs(x(z,t)-1/pe*diff(x(z,t),z)=dydub,x(z,t)=x[N+1](t),t=0,bc2):
> eq[0]:=bc1:
> eq[N+1]:=bc2:
> eq[m]:=subs(diff(x(z,t),z$2)=d2ydu2,diff(x(z,t),z)=dydu,diff(x(z,t),t)=dydu,x(z,t)=x[m](t),z=m*h,PDE):
> for i from 1 to N do eq[i]:=subs (m=i,eq[m]);od:
> x[0](t):=(solve(eq[0],x[0](t)));

> x[N+1](t):=solve(eq[N+1],x[N+1](t));

> for i from 1 to N do eq[i]:=eval(eq[i]);od:
> eqs:=[seq((eq[i]),i=1..N)]:
> Y:=[seq(x[i](t),i=1..N)];

> A:=genmatrix(eqs,Y,'B1'):
Error, (in linalg:-genmatrix) equations are not linear

> evalm(B1);

[B1[1], B1[2], B1[3], B1[4], B1[5], B1[6], B1[7], B1[8], B1[9],

B1[10]]

> B:=matrix(N,1):for i to N do B[i,1]:=B1[i]:od:evalm(B);

> h:=eval(L/(N+1));

> A:=map(eval,A);

> if N > 10 then A:=map(evalf,A);end:
> evalm(A);

> mat:=exponential(A,t);
Error, (in linalg:-matfunc) input must be a matrix

> mat:=map(evalf,mat):
> Y0:=matrix(N,1):for i from 1 to N do
> Y0[i,1]:=evalf(subs(x=i*h,rhs(IC)));od:evalm(Y0);
Error, invalid input: rhs received IC, which is not valid for its 1st argument, expr

> s1:=evalm(Y0+inverse(A)&*b):
Error, (in linalg:-inverse) expecting a matrix

> Y:=evalm(mat&*s1-inverse(A)&*b):
Error, (in linalg:-inverse) expecting a matrix

> Y:=map(simplify,Y):
> Digits:=5;

Digits := 5

> for i from 1 to N do x[i](t):=evalf((Y[i,1]));od:
Error, invalid subscript selector

> for i from 0 to N+1 do x[i](t):=eval(x[i](t));od;

> setcolors(["Red", "Blue", "LimeGreen", "Goldenrod", "maroon",
> "DarkTurquoise", "coral", "aquamarine", "magenta", "khaki", "sienna",
> "orange", "yellow", "gray"]);

["Red", "LimeGreen", "Goldenrod", "Blue", "MediumOrchid",

"DarkTurquoise"]

> pp:=plot([seq(x[i](t),i=0..N+1)],t=0..10,thickness=4);pt:=textplot([[0.28,0.15,typeset("Follow the arrow: ",x[0],"(t), ..., ",
> x[N+1],"(t).")]]):
Warning, unable to evaluate the functions to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct

pp := PLOT(THICKNESS(4), AXESLABELS(t, ""),

VIEW(0. .. 10., DEFAULT))

> display([pp,pt,arw],title="Figure 5.13",axes=boxed,labels=[t,"x"]);
Error, (in plots:-display) expecting plot structures but received: [arw]

In advance, thanks for the time of reading it!

Regards

Ozlem

How to group action on vector space in maple

team-iterator.mw
sample.xls

Howdy

I'm trying to import data from this spreadsheet into this program authored by C.Love.http://www.mapleprimes.com/questions/200480-Product-Grouping

Both files are in the same directory. it imports the data (to some degree), but has problems with order, when decimal points are introducing, also duplicates . see my annotations on the mw file.

Hi to you,

Lets do this;

.1234567891*10^10 +.5 - 1234567892;
                                                   0.

the result is -0.5 and not 0.

I'm new in Maple ... can you help to understand the problem?

Thanks in advance.