Hi
is possible to save the dsolve results for a numerical integration? so that i can reload them with out re-run the integrator.
 

hi, i am trying to find a minimal value for an expression

orginally the expression comprised of two variables t and a

after taking a definite integral from t=0..t=1, the expression should only contain a

and using the commands, i found:

2 question

one, how do you plot two graphs together of f(x,y)= x - x - y + y and it's tanget at plane (1,1). i can do it individually but is it just simple as putting them in one notation in plot command?  for f(x,y) i used plot3d(f(x,y)) from -pi to pi for both x and y but don't know how to put tangent in at plane (1,1)

two, how apporoximate f(x,y) = y / x by a polynomial of degree 6 in x-1 and y+1.

any hints or examples  are much appreciated.

thx

Hey guys, I want to plot a differential equation (I'm looking for something a 2d direction field plot) The differential equation is a composition of piecewise functions and a cubic spline. I have to use the subs() call to convert the function h(t) into a numeric (i dont really understand this part but was told to do this). Anyways I need the DEplot error explained to me. Here I show all of the relavent code leading up to the error: with(CurveFitting): with(DEtools): z := t -> 4.713*sin((1/22356)*Pi*t)+.743*sin((1/21600)*Pi*t)+.964*sin((1/22788)*Pi*t)

does any one know if it is possible to solve numerically a ODE sys write in matrix form without first evaluate is as a set of equation?

for example my system is y'(x)=A(x,y).b(x,y)
where y'(x) and b(x,y) are Vectors and A(x,y) is a matrix

so i would solve it numerically without doing first the dotproduct symbolically. I woud do this because my system equation is constitudet not from a simple matrix.vector but by large matrix inversion so do it symbolically first take a lot of time and memory.

When I do an integral Maple sometimes spits out ridiculous answers.... I don't have an example off hand but oft it will give me trig functions that it SHOULD evaluate. Last night at my lab I was trying to do a taylor series that involved sine squared and to the fourth, and instead of giving me NUMBERS like I needed it left it in terms of sine which was utterly useless to me!

How can I assign an argument to the real numbers in an interval?

I have a matrix M which is 3x4.  I need add a fourth row to it.  I've been trying

 

E:=Matrix([ [M], [0,0,0,1] ])

and

E:=Matrix([ [Row(M,1)], [Row(M,2)], [Row(M,3)], [0,0,0,1] ])

But neither of them worked.  How would I do this?

Thanks,
Dave

Hi, I am trying to find a general solution for a special case of the 4x4 Riccati Equation. My worksheet chugs for 5 hours and 2gigs of memory before crashing. Am I posing the problem incorrectly? Or will more memory help (and if so, how much memory)? > with(LinearAlgebra); > A := Matrix([[ZeroMatrix(2), IdentityMatrix(2)], [ZeroMatrix(2), Matrix(2, symbol = a)]]); > B := Matrix([[ZeroMatrix(2)], [Matrix(2, symbol = b)]]);

Hi all,

 

 

Hi all! Please help me to simplify the following expression: ex1 := C10*C20*a^2+2*C10*C20*a*b+C10*C20*b^2-m*u^2*a*C10+m*u^2*b*C20+1/2*e1*e2*a^2+e1*e2*a*b+1/2*e1*e2*b^2; 1, I've tried the followings: collect(ex,e1*e2); Error, (in collect) cannot collect e1*e2 2, then I've read some advice here in the forum, and tried this: subs(e1*e2=z,%); collect(%,z); S0_temp2:=subs(z=e1*e2,%); This doesn't works as well. It simply doesn't substitutes z for e1*e2. My goal would be to get something like this: (a+b)^2*(C10*C20+1/2*e1*e2)-m*u^2*(a*C10-b*C20); Thanks!

Hi,

I'm just playing about with Maple's functions to see what they do. I'm confused by the behaviour of "evalb". When I enter:

I want to learn how to analytically and graphically analyze discrete time recursion equations such as the following: N(t+1) = (1+b)(1-d)N(t) in Maple 12 because Mathematica decided to crap out on me right before I have to give a professional talk (SHAME ON YOU STEPHEN WOLFRAM!!). Does anybody have a good direction to point me in? Basically, in Mathematica, what I would do is: N[t_, b_, d_]:=N[t,b,d]=(1+b)(1-d)N[t-1,b,d]

hey i'm trying to learn how to use maple and can't seem to figure out why this is wrong. i don't really know what "nops()" does either. 

 

with (linalg);

*insert equations, matrix and Groebner here and get a whole bunch of z values *

 

zvals:=[fsolve(polz)];

for i from 1 to nops(zvals)

  Error, unterminated for loop

do

   Error, unable to parse

myx:=zvals[i];