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### Error, (in f) unable to store .......................

May 27 2014
0 2

Hello Hello everybody
I have to solve the following differential equation numerically

 > restart:with(plots):
 > mb:=765 : mp:=587 : Ib:=76.3*10^3 : Ip:=7.3*10^3 : l:=0.92 : d:=10: F:=490: omega:=0.43 :
 > eq1:=(mp+mb)*diff(x(t),t\$2)+mp*(d*cos(theta(t))+l*cos(alpha(t)+theta(t)))*diff(theta(t),t\$2)+mp*l*cos(alpha(t)+theta(t))*diff(alpha(t),t\$2)+mp*(d*diff(theta(t),t)^2*sin(theta(t))+l*(diff(theta(t),t)+diff(alpha(t),t))^2*sin(alpha(t)+theta(t)))-F*sin(omega*t)=0;
 (1)
 > eq2:=(mp+mb)*diff(z(t),t\$2)-mp*d*(sin(theta(t)+alpha(t))+sin(theta(t)))*diff(theta(t),t\$2)-mp*l*sin(alpha(t)+theta(t))*diff(alpha(t),t\$2)+mp*(d*diff(theta(t),t)^2*cos(theta(t))+l*(diff(theta(t),t)+diff(alpha(t),t))^2*cos(alpha(t)+theta(t)))+9.81*(mp+mb)-F*sin(omega*t)=0;
 (2)
 > eq3:=mp*(d*cos(theta(t))+l*cos(alpha(t)+theta(t)))*diff(x(t),t\$2)-mp*(l*sin(theta(t)+alpha(t))+d*sin(theta(t)))*diff(z(t),t\$2)+(Ip+Ib+mp*(d^2+l^2)+2*mp*d*l*cos(alpha(t)))*diff(theta(t),t\$2)+[Ip+mp*l^2+mp*d*l*cos(alpha(t))]*diff(alpha(t),t\$2)-mp*sin(alpha(t))*(l*d*diff(alpha(t),t)^2-l*d*(diff(alpha(t),t)+diff(theta(t),t))^2)+mp*9.81*l*sin(alpha(t)+theta(t))+mp*9.81*d*sin(theta(t))=0;
 (3)
 > eq4:=mp*l*cos(alpha(t)+theta(t))*diff(x(t),t\$2)-mp*l*sin(alpha(t)+theta(t))*diff(z(t),t\$2)+(Ip+mp*l^2+mp*d*l*cos(alpha(t)))*diff(theta(t),t\$2)+(Ip+mp*l^2)*diff(alpha(t),t\$2)-mp*9.81*l*sin(alpha(t)+theta(t))+l*d*mp*diff(theta(t),t\$1)^2*sin(alpha(t))=0;
 (4)
 > CI:= x(0)=0,z(0)=0,theta(0)=0,alpha(0)=0,D(x)(0)=0,D(alpha)(0)=0,D(z)(0)=0,D(theta)(0)=0;
 (5)
 > solution:=dsolve([eq1,eq2,eq3,eq4, CI],numeric);
 Error, (in f) unable to store '[0.]/(0.17571268341557e16+[-0.25659510610770e15])' when datatype=float[8]

I don't know why it says : Error, (in f) unable to store '[0.]/(0.17571268341557e16+[-0.25659510610770e15])' when datatype=float[8]

Help pleaase!

thank you !!!

### Fix a syntax error in my simple function (please h...

March 31 2014
0 1

firstly apologies in advance for stuff in this question such as "triangle symbol",  my computer is pretty old.

ok so i was confused a bit here, what i'm trying to do is write a maple procedure that computes Af for a given f contained in V . except we only need to correct the bug in the script below. This script demonstrates such a procedure in the case that omega is a square. The domain is given here as the negative set of a function F contained in V .  I have left in notes where/what i think we need to do but i dunno how to...

N:=10 ; # Global Var
F:=(x,y)->sgn(abs(x-N/2)+abs(y-N/2)-N/4);
Average := proc(F, f0) local f, i, j;
f := f0; # !!!!!!!!!!!!!! something is bad here...
for i to N do for j to N do
if F(i, j) < 0 then
f[i, j] := (f0[i - 1, j] + f0[i + 1, j] + f0[i, j + 1] + f0[i, j - 1])/4 ;
end if;
end do;end do;
return f;
end proc;
f0:=Matrix(N,F); # just to have something to test the procedure
Average(F,f0); # does not return the expected average, modifies f0

the necessary information we were given to produce this so far was..

Let N be a positive integer and [N] = {i contained in N | 1<= i <=N }  Let "Omega" C {(i,j) contained in [N] x [N] | 2<=i,j<=N-1} be a subset. Let V = R^([N]x[N]) be the vector space of real valued functions [N]x[N] -> R
and A, "triangle symbol":V->V (average) and "triangle symbole" (Laplacian) be the linear maps such that
[Af](i; j) = f(i; j)      if (i; j) not contained in "Omega"   OR

[f(i, j + 1) + f(i, j - 1) + f(i + 1, j) + f(i - 1, j)]/4 if (i,j) is contained in "Omega"

["traingle symbol"f](i,j) =  0 if (i,j) isnt contained in "Omega"   OR

( f(i,j) - [f(i, j + 1) + f(i, j - 1) + f(i + 1, j) + f(i - 1, j)]/4 )    if (i,j) is contained in "Omega"

### Problem viewing old Maple Classic worksheets in Ma...

September 18 2012
0 5

I found some old Maple 6 worksheets that I wrote in 2003 and I want to see what's in them and probably transfer at least some of the content to new worksheets.  Most of them I can view just fine with Maple 16 standard interface but at least one of them comes out looking like all of the lines have been printed on top of each other --- completely illegible.  Now I can read the worksheet using Maple classic interface on my machine at home, but both of my machines at...

### Jet Engine Model...

July 11 2011
0 2

I'm looking for an older worksheet called something like 'Basic Jet Engine Model' originally created for Maple V.

Does anyone recall such a worksheet?

### Mapleprimes alternative...

June 23 2010
2 4

I propose a huge mapleprimes suggestion.  What would happen if you re-opened the old mapleprimes site?

I propose you run both mapleprimes old and mapleprimes new at the same time for a few of months and see which site becomes more active.  Users will gravitate towards the one that is better layed out, easier to navigate, and seems to work better.  Mapleprimes can track which site becomes more active.  Currently the data of comparing...

### What's with all the old posts showing up with no r...

June 07 2010
1 4

Why are old posts with no recent replies showing up in the all recent category??

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