Hi, is there any best turorial to learn maple for Mathematics. thanks 

the calculation is like the following command, the result in the picture

restart;
with(VectorCalculus);
SetCoordinates(spherical[r, theta, phi]);
Fv := rho*VectorField(`<,>`(v[r](r, theta, phi), v[theta](r, theta, phi), v[phi](r, theta, phi)));
Divergence();
Divergence(Fv);

1) when the Divergence act on the Fv, then it will be expanded, which is lengthy and not like most book's formulation , especially when I want to continue for a Conversation law like in fluid mechanics, this will be too long and a messy for later check.

could there be a way to not expand this result, just as the eq(3) like.

2) when I want to calculate the Divergence of Fv, I must construct a VectorField at first, but this is in components way, is there a quick way for Vector Field Function

dsolve.mw

Hi all, is there anyone who can help me to solve the ODE equation?

I attached two files here....

It really annoyed me ...         :-(

 A'(t)=20+0.03*A(t)-0.00005*A(t)*Q(t)-0.0002*A(t)*Q(t)-0.0743*A(t)-12,

B'(t)=0.03*B(t)+0.00005*A(t)*Q(t)+0.0002*A(t)*Q(t)-0.0743*B(t)-0.01072*B(t),

C'(t)=0.01072*B(t)-(0.0743+0.0123)*C(t),

P'(t)=15+0.03*P(t)-0.0001*P(t)*B(t)-0.0743*A(t)-10,

Q'(t)=0.03*Q(t)+0.0001*P(t)*B(t)-0.0743*Q(t)-0.25*Q(t),

R'(t)=0.25*Q(t)-(0.0743+0.0123)*R(t),

X'(t)=25-0.0003*X(t)*B(t)-0.0743*X(t)-10,

Y'(t)=0.0003*X(t)*B(t)-0.0743*Y(t)-0.3*Y(t),

Z'(t)=0.3*Y(t)-(0.0743+0.0123)*Z(t).

Initial conditions

A(0)=150,B(0)=30, C(0)=10,P(0)=130,Q(0)=45,R(0)=10,X(0)=85,Y(0)=30, Z(0)=20.

Can I plot the graph between {A(t),B(t),C(t),P(t),Q(t),R(t),X(t),Y(t),Z(t)}and time t{0,100}.

Hi, 

     I've been playing around with the Physics package, and I'm confused on evaluaing derivatives of explicit funcitons of the coordinates. This code below doesnt behave as I would think. I'm trying to define z as a function of X[mu]*X[mu], and take diff(z, X[mu]). You can see that each method d_, diff,  disagree and none are satisfactory ansers. (Maple 2015, Windows 8.1 64-bit, Intel i5 Haswell) 

# Declare coordinates for 2 dimensions, flat space

restart:
with(Physics):
Setup(mathematicalnotation = true, dimension = 2):
Coordinates(X):

# Method 1: Using Define and various differential operators
Define(z):
z :=sqrt(R^2-X[mu]*X[mu]);
d_[mu](z(X));
d_[1](z(X));
diff(z, x1);  #This one is correct
diff(z, X[mu]); # off by 2

# Method #2: Using functions
# Off by a factor of 2
z2 := mu -> sqrt(R^2-X[mu]*X[mu]);
diff(z2(mu), X[mu]); # off by 2

 PhysicsDiffBug.mw

I want to make the model which moves along the specific direction (translational), So I used the "prismatic joint" to give the direction that I want to enforce. However, "Prismatic joint" only offers the direction along the "X", "Y", and "Z" axes though I want to give other direction.

Is there any way to give the specific direction (vector) to make my model move in that way ?

Hi all,

I've been working on this problem for a while and only need to figure out why the function vector is returning zeros every time I call the procedure. The problem statement is in the file I attached to this.

If any of you could help me, I would be a happy guy.

File: 1.2.mw

Just as the title says: How do I avoid Maple Prompt to appear automatically?

When writing a code in Maple Prompt and hitting enter, a new [> is created and I can't delete it. Which is unfortunate, for most of the time I want to write some TEXT afterwards, not more code.

Sometimes it doesn't happen, but I can't find the logic in it. Any ideas? Much obliged!

For an example, see this post:

http://www.mapleprimes.com/questions/203735-Print-To-Pdf-Results-In-Blank-Space

2nd picture. I asked it as a BTW-question.

Thanks in advance

hello

i have some problem when iuse the digital libray with the delay components:

i have this error: delay variable not found in dependent variable list, [`Main.TransportDelay1.x`(T)]

it seems that the delay function in the modelica language is not well treated in MapleSim . At this level:

equation
    y = if 0 < delayTime then if delayTime <= time then x_delayed else y0 else pre(x);
    x_delayed = integer(delay(x, delayTime));
end Modelica.Electrical.Digital.Delay.TransportDelay;

Thank you for your help.

hi friends

i have a problem in maple with an error

Read'dsnumsort.map';
dsnumsort(Ns(0),[x,y,z]);
for i from 0 to 1000 do;
T:=i/25;
NsT:=Ns(T):
X[i]:=rhs(NsT[C1]); Vx[i]:=rhs(NsT[V1]);
Y[i]:=rhs(NsT[C2]); Vy[i]:=rhs(NsT[V2]);
Z[i]:=rhs(NsT[C3]); Vz[i]:=rhs(NsT[V3]);
KepVec[i]:=convert(crossprod([X[i],Y[i], Z[i]],[Vx[i],Vy[i], Vz[i]]),list);
KepAbs[i]:=norm(KepVec[i],2);
od:

pacecurve({[seq(X[i],Y[i],Z[i],i=0..1000)],[[-1/(2),0,0],[1/(2),0,0]]},labels=['x','y','z']);

but i see:

Error, invalid input: seq expects 2 arguments, but received 4

can you helpe me?

Thanks

Hi I have some problems with the inert view of the limit command.

I have upload the file. 

bug_limit.mw

Thank you.

Hello!

Please help solve this equation!

restart;

Dd:=4.9*10^(-10):
n:=4.5:
m:=3.5:
ny:=20:
B:=1.47*10^(-11):
H1:=70:
H2:=20:
H:=100:
b1:=40:
b2:=80:
delt_y:=H/ny:
A_max:=b1*H1+b2*H2+10*b1:
M:=1000:



b:=y->piecewise(`and`(y>=0,y<=H1),b1,`and`(y>H1,y<H1+H2),b2,`and`(y>=H1+H2,y<=H),b1):
y:=0: eq:=0:

for j from 1 to ny do
y:=(j-1)*delt_y+delt_y/2;

eq:=evalf(eq+b(y)*sign(y-y0)*abs((y-y0))^(1/n)*delt_y);
end do;

#eq=0, y0-?
sol1:=fsolve({eq=0},{y0});

Hi

I'm trying to use the command: DocumentTools[Retrieve](path,label), but i recieve the message "unable to retrieve label reference" no mather what i do. When i use the GUI: Insert - reference and get the value it works fine, but in that way I can't assign the value to a variable in the document.

here is an example:

The document i want to retrieve a value from:

restart;

a := 5;

#a gets the label (1)

The document i want to retrieve the value to:

restart;
with(DocumentTools);

path := FileTools:-JoinPath(["test.mw"], base = worksheetdir); = "C:\Users\Nicolai\CloudStation\Nicolai\Skole stof\Sem 7\test.mw"

Retrieve(path, "());
Retrieve(path, "(1)");
Retrieve(path, "a");

#None of the above works

Is it even possible to do such thing?

with best regards

Nicolai

with(Physics) :
t:=Intc(Dirac(k1+k2+k3)*phi(k1)*phi(k2)*phi(k3),k1,k2,k3) ;

# how to force
Fundiff(t,phi(-k));

# to find
3*Intc(Dirac(k2+k3-k)*phi(k2)*phi(k3),k2,k3) ;

hi friends

i have a problem in maple with an error

 restart:
 with(plots):with(linalg):
 r:=sqrt((xi-x)^2+y^2+z^2):
 sigma:=m/l:#linear mass density
 U:=Int(G*sigma/r,xi=-L/2..L/2);
 U:=normal(value(U));
 Us:=subs(G=1,m=1,L=1,z=1.5,U);
 plot3d(Us,x=-2..2,y=-2..2,axes=boxed,style=hidden,color=red,orientation=[-80,-130],numpoints=35^2,labels=['x','y','U']);

after this i see :

 Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct.

can you help me?

Thanks for your time

Best regards