ex1 := {
diff(x1(s),s$2) - 2/x2(s)*diff(x1(s),s)*diff(x2(s),s) = 0,
diff(x2(s),s$2) + 1/x2(s)*diff(x1(s),s)^2-1/x2(s)*diff(x2(s),s) = 0
};
sol := dsolve(ex1);
ic := {x1(0)=0.1, x2(0)=0.1};
dsol := dsolve(ex1 union ic, numeric, range=0..1);
odeplot(dsol);

Error, (in dsolve/numeric/SC/IVPsetup) initial conditions must be numeric

initial condition has already set 0.1 but still ask for must be numeric why?

I have a problem with radiobutton

i have 3 types of fricction, and each radio button has one type of it.

I have a problem when i select one type of friction don´t plot it

that is the code  RBFEstatica is a radiobutton of type static fricction

if GetProperty(RBFEstatica,value) = true then

DocumentTools[SetProperty](Label0,caption,estatica);

p1 := 0;
 p2 := 0.1;
 deltav1 := piecewise((abs(x2q1(t)) > 0 and abs(x2q1(t)) < 0), p1, p2);

Hello all,

Im trying to apply the working of the algorithm shown below to a more complex one(attached). The simple algorithm produces separate spreadsheets for different values of j. In the attached algorithm Im trying to produce different spreadsheets for different values of 'angle1'. I have applied the same structure but with no success. 

Can someone please have a look at my code and point me to my mistake?

Any help is really appreciated

Hello everybody,

   I have to solve the following differential equation numerically

dsys1 := {0.27e-2*(diff(x(t), [`$`(t, 2)])) = -3*10^(-4)*sqrt((diff(x(t), t))^2+(diff(y(t), t))^2+(diff(z(t), t))^2)*(diff(x(t), t))-(2.25*10^(-4)*8)*(diff(y(t), t)), 0.27e-2*(diff(y(t), [`$`(t, 2)])) = -3*10^(-4)*sqrt((diff(x(t), t))^2+(diff(y(t), t))^2+(diff(z(t), t))^2)*(diff(y(t), t))+(2.25*10^(-4)*8)*(diff(x(t), t)), 0.27e-2*(diff(z(t), [`$`(t, 2)])) = -3*10^(-4...

I am not able to use the Maple 15, because after it starts up, I receive an error ""the kernel loader cannot find Maple engine..."

What does it means and how to solve it?

Thanks

Consider the simple loop below:

> for q  from 1 by 1 to 12 do;

> 
> if inter[q] <= B then xz[q] := inter[q] end if;
> 
> end do;

inter[1] to inter[12] is defined previously

B is also calculated beforehand.

My problem is that Maple insists on looking for inter[13] and xz[13]. My range is between 1 and 12 so Maple shouldnt be doing this.

Hi all. This is porbably a very elementary question. Maple outputs something of the form  " X +  0. I" after a computation, where X is a number. I'm confused as to what 0. I is. My first thought is that it's 0.1 * I, but then squaring X +  0. I  gives back X^2 + 0. I instead of the expected X^2 - 0. 01 + 0.2 X I. Could someone explain to me what Maple means by that? Thanks!

X +  0. I

Dear Maple Users

I was looking forward to having the Units package improved in Maple 15. Units are indeed converted to SI Units when direct calculations are made. It is a disappointment though that this conversion doesn't occur when solving equations as the example below show:

Unfortunately Maplesoft mix up their announcements for news in version 15 of Maple with...

Hi all,

I want to save a plot into Array or other and re-plot it by pointplot.

restart:with(plots):

f:=x->cos(x)+cos(x)^2;

plot(f(x),x=0..2*Pi);

With Array, I want to determine dx (step) of the plot (Array) and the dimension of Array (number of line and column).

If Pk:=plot(f(x),x=0..2*Pi); is Array, I can reproduce the plot as:

ef := {seq([Pk[i,1], Pk[i,2]], i = 1 .. N)}: # Pk[i,1] is x and Pk[i,2] is f(x), N number of line of Array

I would like to do the following.

Ive got variables a(z) where z(tau). Now I would like to do something like:

>> t = z(tau);

>> a := a(z);

>> diff(a,tau);

  == (da/dz)*(dz/dtau)

How come that I don't have a commenter badge?

I'm pretty sure that I left more than 10 comments on this site.

Could comment 10 times to this question if necessary.

Alec,

Thank you very much for your explanation!

Do you known about any book or other texts that explain more about it ?

I would like to create some examples of maximum likelihood estimation using this symbolic approach. 

Best regards,

Pedro

Hello,

I am having trouble in defining multivariable functions. For instance, when I define the follow code:

assume(n>0)

 f:=(x_1,x_2,...,x_n) -> sum(x[i],i=1..n)

I get the error: Error, invalid operator parameter name.

How can I define this type of function when the number of variables is conditional on "n" ?

Hi,

I have the function:

restart: with(plots): with(OrthogonalExpansions): with(DiscreteTransforms):

f:=t->piecewise(t<0,0,t<1,t,t<2,2-t,0);

The Fourier coefficients a[0], a[i] and b[i] can be calculated by:

T:=2: Trig:=FourierSeries(f(t),t=0..T,n,'Coefficients');

a[0]:= op(1, Coefficients);a[i]:= op(1, op(2, Coefficients))[1];b[i]:= op(1, op(2, Coefficients))[2];

I want to calculate those coefficients a[0...

Defined a demand function:

x:=(p,w)->w/(p[1]+p[2]+p[3])*Vector([p[2]/p[1],p[3]/p[2],p[1],p[3]])

The Slutsky Matrix is calculated as Dpx(p,w) + Dwx(p,w) x(p,w)^T with Dpx(p,w) = Jacobian for p1, p2, p3 and Dwx(p,w) is a column vector of the derivate of x1, x2, x3 in respect to w.

Step by step:

Dxp := Jacobian(x(p,w),[p[1],p[2],p[3]])

yields the correct Jacobian.

For Dwx I've tried several different methods, i.e.

Dwx := Jacobian(x(p,w),[w...