substitution problem...

Hello,

I have an expression:

y:=a*10^(x/20)+b*10^(x/10);

(x is real here)

I 'd like to write this epxression in the form of y=a*K+b*K^(2) with Maple using 10^(x/20)=K substitution.

I have tried it with subs and algsubs but they don't work here for me.

(Originally I had a more complicated expression of this type).

Parameters for controlling execution of numapprox[...

Hello Maple wizards,

I'm trying to use numapprox[infnorm] to locate the L-infinity norm of functions such g(y) on the range 0.0..1.0 at the bottom of this post. Plotting shows that the function has an range of width 10e-3 that contains a minimum near y=0.9965, but infnorm() doesn't find it unless the range is artifically constrained to be close to the minimum.  I'm using infnorm() in a proc's loop, so manual control of the range based on the graph is not an appealing option.

Unit Circle and Triangle...

I am trying to graph a unit circle with a triangle in the second quadrant on one set of axes.  Can anyone help with this?  I'm just learning Maple and am having a hard time with it.  Thanks!

system of ODE's in matrix form...

Suppose you have a system of linear ODE's and you want to convert them into one matrix equation. Basically what you do with algebraic eqs using GenerateMatrix. Is there a Maple command to do that? Obviously, one could you use the lagrangian if the eqs happen to represent a dynamic system but that's not what I am looking for. And the second part of the question, once you have the matrices is there a way to export them and ,say, run a finite element analysis with them?

thanks a lot

dimitrios

Iterative process...

Hi,

I need to solve iteratively the following equation: Y=A(t) *B(Y) using the values of the following two sets .

A=[0.9,0.75,0.6,0.2,0.08,0.06,0.051,0.05]

2-D animation plots...

I would like to be ale to define a function such as f(x)= exp(a*x) and have it display the gausian curve and animate as the values of x change.  The software keeps treating a as a variable of it's own, I want to treat it as a constant.

Partial Fractions Finder...

This is a unique, powerful and useful tool that will help students do decompositions of rational functions. See the attached worksheet. Also, you can view an interactive video tutorial that shows you how to use the Partial Fractions Finder: (Ctrl + click on link below) Video Tutorial: Partial Fractions Finder

Approximate a nonlinear DE for use in 3D graph...

I need to plot [cos(v)*x(t), sin(v)*x(t), v] where x(t) is the solution to diff(x(t),t)=sqrt(1/(-x(t)^2+1)-1) I can use DEplot to show me an approximation of x(t), which is what I want, but I need to graph the afformentioned 3d plot. I am not having success with DEPlot3D, because I can't figure out how to plot it with the cosine and sine functions shown above. I would appreciate any help.

How do I plot parametric surfaces?...

I've searched quite extensively across the internet and cannot seem to find my answer, even on this forum or in maple help.

I'm trying to plot parametric surfaces using the (u,v) notation or in other words

cos(v)i + sin(v)j + (u)k

so have tried in maple as such:

cylinder := (u,v) -> [cos(v), sin(v), u];

Derivative of Matrix...

Hello,

I was wondering what the easiest way to calculate the derivative of a matrix is?

So far I am trying:

> with(LinearAlgebra);
with(VectorCalculus);
> A := Matrix(2, 2, {(1, 1) = 1, (1, 2) = x^2, (2, 1) = 4*x^7, (2, 2) = x^3});
Matrix(%id = 163320844)
> B := D(A);

uneval parameters...

hi.

when i want to modify a parameter it's easy:

test1 := proc(x::uneval)
x:=eval(x)+1;
NULL;
end proc;

x:=5;
test1(x);
x;

ok x is now 6

How to do that with lists of names ?
ie writing a procedure test2 so that I can do that:

x:=10;
y:=20;
test2([x,y]);
x,y;
11,21

thank you

differentiability test...

Dear all:

I wonder if there is any function in Maple checking whether a given function is (m-th) differentiable or continuous?

Thanks,

Peter

System of ODE with ICs...

Hi,

I have the following set of ODE:

sys := diff(U(t), t) = Itot/C-U(t)/(R*C), diff(U(t), t) = (Itot-I1(t))/C, diff(U(t), t) = I2(t)/C

The general solution is easily obtained by:

sol1 := dsolve({sys})

SOLUTION: sol1:={U(t)=Itot R+(e)^((-(t)/(R C))) _C1,I2(t)=-((e)^((-(t)/(R C))) _C1)/(R),I1(t)=(Itot R+(e)^((-(t)/(R C))) _C1)/(R)}

However, I cannot get the solution for initial conditions. In fact, we only need one initial condition, to solve for _C1:

IC:=U(0)=0  #Alternatively: I1(0)=0 or I2(0)=Itot.

How do I invert (revert) the following power serie...

Let w =f(z) = sum of z^(k+a) / (k + a)

where k= 0 to infinity and a is a nonzero parameter.

I need to find the inverse of this series, z = g(w). The powseries examples in Maple Help don't help. They don't work on my example, with a symbolic variable, a, stuck in there.  I hope that if I see about 7 or 8 terms of the inversion, I will get the general pattern.  I have tried to compute the inverse directly from the Lagrange Inversion Formula, but the complexity always grows too quickly for me to complete the solution, no matter which shortcut I try to take.