Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 Help Me ! » Algebra problem! » 2011-03-30 09:18:36

gftrigo
Replies: 3

Hi!

I have this algebra problem that has been puzzling me.

I have this matrix multiplication:

where A and theta are a 3x3 matrix and a 3x1 vector, respectively, both dependent of x and D and S are 3x3 constant matrices.
A is a symmetric matrix, D is a diagonal matrix and S is a skew-symmetric matrix.
I need to arrange this into the form:

where C is a constant matrix and F(x) is a vector function of x. The dimensions of these matrix and vector are not important, as long as the result of the multiplication is 3x1.
I need to isolate the x dependent part on the right side of the term in order to apply a control algorithm.

Does anyone know how to do this?

Thanks!

#2 Re: Help Me ! » Recursive sequence limit » 2011-03-18 01:32:13

Hi bobbym!

Indeed it is not a homework, I really need to understand the steps that lead to the answer.
I really appreciate your help and patience!

#4 Re: Help Me ! » Recursive sequence limit » 2011-03-17 23:52:50

Thank you a lot gAr!

bobbym can you explain me the inequalities please?

#5 Re: Help Me ! » Recursive sequence limit » 2011-03-17 23:41:55

Thank you gAr!

yes, the roots of the characteristic polynomial, I remember now!

I was trying to solve the inequalities of abs(r1)<1 and abs(r2)<1 but all I can get is:

with abs(r1)<1 I get:

which also gives

from abs(r2)<1 I get:

which gives

Is this right? I can't seem to make the final step to get what bobbym got.

#6 Re: Help Me ! » Recursive sequence limit » 2011-03-17 22:41:16

Hi! Wow! thank you!

gAr can you explain me how you solved the recurrence to find that expression for ak (on post #2)?

Thanks!

#7 Help Me ! » Recursive sequence limit » 2011-03-17 14:39:45

gftrigo
Replies: 19

Hi!
I have been stuck with this sequence:

I need to find an expression for the values of a and b for which the sequence converges to 0.

Any suggestion or solution would be very welcome!

Thank you!

Board footer

Powered by FluxBB