Hello there, could someone tell me how to input this differential equation?

d²x/dt² - (3)dx/dt + 2x = 2t -3 

x=2, t=0, dx/dt=4

So it looks like radians work.

Why does degrees fail and how do I get degrees work?

How do you guys like to access pi? Do you keep a symbol of it around in a random document to open? 

http://i.imgur.com/07o1dyH.png

Let A(x , 2 , -1) ,B(0, y , 1) ,C(3 , 4 , -2) , AB=AC and ABC is isosceles right triangle. Find x and y ?

How would you insert a label-coordinate in this command:

textplot3d([subs(E[11]=0,x[11]),subs(E[11]=0,y[11]),subs(E[11]=0,z[11]),"Planet"]):

What is the command for filling the space between two circular spacecurves? Something like a Saturnian ring?

    Intersection of surfaces:

x3-.25*(sin(4*x1)+sin(3*x2+x3)+sin(2*x2))=0;  (1)

(x1-xx1)^4+(x2-xx2)^4+(x3-xx3)^4-1=0;          (2)   

   Surface (1) and a set of surfaces (2). Point (xx1, xx2, xx3) belongs to (1). Moving along the surface (1), we compute its intersection with the surface (2).
   The program is very simple and its algorithm can be used for many other combinations of equations.

intersection_of_surfaces.mw  

Hi there,

I'm trying to get the values from the output of a dsolve command.

I have a system of differential equations:

de1 := diff(V(t), t) = V(t)-(1/3)*V(t)^3-W(t)+Ie;
de2 := diff(W(t), t) = 0.8e-1*(V(t)+.7-.8*W(t))

For a range of the independent variable t and for some given values of the parameter Ie, I would like to get the value of the dependent variable V, as well as its minimum/maximum values for each Ie.

Can anybody suggest a solution please?

This is the worksheet: MaplePrimes_dsolve_min-max.mw

Thanks,

jon

Hello all,

I'm experiencing an aggravating issue when substituting numerical values into a symbolic expression.  I'm using Maple 14.  I believe the issue may be related to floating point precision.  Either way, it's ruining my life.  If anyone has a solution or a work-around, I'd be most grateful.  The following code reproducibly produces the anomolay on my machine:

vx := Vector( 4, symbol=x ):

# A numerator and a denominator. They're equal.
num := (x[1]*x[3]+x[1]*x[4]+x[2]*x[3]+x[2]*x[4])^2:
den := ((x[1]+x[2])^2*(x[3]+x[4])^2):

# Prints true...
evalb(num=den);

# This equals zero
y := 0.1 - 0.1*num/den;

# Prints 0...
simplify(y);

# Prints 0...
simplify(subs(x[3]=1,x[4]=3,0.1-0.1*num/den));

# Prints 0...
simplify(subs(x[3]=1,x[4]=3,y));

# Prints 0.1 x 10^-10 !?!?
simplify(subs(x[3]=1,x[4]=2,y));

Hello,

I have a little problem. I have a system of ODEs, I can solve (with numeric solve) it but I can't plot it...
Any idea to help ?

Thank you !!

Here is my code:

with(DEtools);
beta := 1; lambda := 5; nu := 1; Delta := 1;


sys := {C(0) = 0, In(0) = .2, diff(C(u), u) = beta*In(u)*s(u)-C(u)/nu, diff(In(u), u) = C(u)/nu-In(u)/lambda+Delta*(diff(diff(In(u), u), u)), diff(s(u), u) = -beta*In(u)*s(u), s(0) = .8, (D(In))(0) = .2}

dsys := dsolve(sys, numeric, [In(u), s(u), C(u)])

plot(dsys[1], u = 0 .. .5, axes = boxed)

And I have this error:

Warning, expecting only range variable u in expression dsys[1] to be plotted but found name dsys[1]


PS: Maple solves the system without any problem:

 dsys(.5);

        [                                              
        [u = 0.5, In(u) = HFloat(0.33305297276372425),
        [                                              

           d                                       
          --- In(u) = HFloat(0.33950703755414946),
           du                                      

          s(u) = HFloat(0.7022184797811994),

                                           ]
          C(u) = HFloat(0.0781621551198558)]
                                           ]

Hi!

I use 'alias' to define variable dependencies.
But when I want to use the result of my calculation as an expression, I bite the dust; I cannot get rid of the dependencies.
Can anyone help me here?

In the simplified example below, I use the independent variables z[3] and z[4] to define z[1](z[3],z[4]) and z[2](z[3],z[4]).
I then introduce a function f[1](z[3],z[4]) and its derivatives df_dz.
I introduce the names dz[1]/dz[3]=Dp[1,3], dz[1]/dz[4]=Dp[1,4] etc...
When I have calculated df_dz[3], however, I cannot insert values of z[2] without affecting Dp[2,3].
Actually, now I have finished my calculation and want df_dz[2,3] to be a regular expression, so that I can insert values of
z without affecting the Dp:s.
How can I convert df_dz[3] to a regular expression?

alias( seq(z[i]=z[i](seq(z[j],j=3..4)),i=1..2)):
alias(f=f(seq(z[j],j=3..4))):
alias(seq(seq(Dp[m,n]=diff(z[m](seq(z[j],j=3..4)),z[n]),m=1..2),n=3..4)):

f:=z[1]-z[2]*z[3]:

for j from 3 to 4 do
df_dz[j]:=diff(f,z[j]);
od:

df_dz[3];
subs(z[2]=4711,df_dz[3]);
whattype(Dp[1,3]);
whattype(z[3]);




function

indexed

Hi there,

I'm relativly new to maple and right now I'm trying to plot a couple of points (as part of a TSP-Solution) by doing the following:

with(plots):

p := [[565,575],[685,595],[700,580],[770,610]];

pointplot(p, connect=true);

Unfortunately it doesn't number the points. What I'm trying to do is that the above four points have a number or an index so I can see which point is where. 

Is there a way to do this?

thanks

restart:

Eq1:=x=(phi*(theta[m]-1/x)/theta[m]+(1-phi)/2);

solve({Eq1},x);

x := (1/4)*(phi*theta[m]+theta[m]+sqrt(phi^2*theta[m]^2+2*phi*theta[m]^2-16*phi*theta[m]+theta[m]^2))/theta[m];

Now plotting the first root

p1:=plot(subs(phi=0,x),theta[m]=0..14,color=red):
p2:=plot(subs(phi=0.1,x),theta[m]=0..14,color=green,linestyle=2):
p3:=plot(subs(phi=0.5,x),theta[m]=0..14,color=blue,linestyle=3):
p4:=plot(subs(phi=1,x),theta[m]=0..14,color=black):
display({p1,p2,p3,p4},axes=boxed,view=[0..14,0..1]);

Note: I'm unable to reproduce the following plot. Any idea?

 SA.mw

I'm a student. I want to purchase oline Maple Student, but I can't.

Please send me a feedback as soon as possible. Thanks.

I am attempting to plot an initial value problem in Maple 18.  I have my equation defined, as well as a general solution and two particular solutions at y(0)=3/4 and y(0)=1/2.  To graph, I entered the command

DEplot(de,y(x),x=-3..3,{[0,1/2],[0,3/4]},dirgrid=[12,12],color=black,linecolor=blue,thickness=2);

but instead of returning a graph, the software gave me the error message

Error, (in DEtools/DEplot/CheckDE) extra unknowns found: sinx

The Maple support site lists this as an unknown error, and as a new user, I'm not sure what to do.  What does this mean?

Hi everyone,

I've been having a problem trying to correct this procedure so that it will accept empty tables as well. This is the code I've been messing up with:

6.10.mw

If someone could help me with this, it would be really appreciated.