Recent content by rockerman

Given two quadratics of the form $f(x) = x'Q_1x$ and $g(x) = x'Q_2x$ and assuming $Q_1$ and $Q_2$ are negative definite matrices, how can I find the lines that are formed by their crossing? here I'm assuming $x \in \mathbb{R}^2$. I'm interested in finding vectors $w_1$ and $w_2$ that are...

great tip micromass! thanx... I don't know, but maybe i just have to look at the problem at the simplest manner possible... the first thing that i did before was: (1) -> A = \left( \begin{matrix} 1 & b/a \\ c & d \end{matrix} \right) by doing so, i was stuck and nothing could be done anymore.

as micromass stated, it is has to do with the definition that you are using... in this case the book (HOFFMAN - Linear Algebra) states as being the rows at any order.

Analysing the first question I found an inconsistency. The matrix could be, say: \left(\begin{array}{cc} 1 & b\\ 0 & 0 \end{array}\right) Is that a problem? because from the point of view of matrices, these two are different.

oh thanx... The problem Consider the system of equations AX = 0 where A = \left(\begin{array}{cc} a & b\\ c & d \end{array}\right) is a 2x2 matrix over the field F. Prove the following (a) If every entry of A is 0 then every pair (x1, x2) is a solution of AX = 0; (b) if ad-bc != 0, the system...

I was limiting my thinking to the most obvious cases of existence of such matrices. many thanks for the help; By now i have only one more doubt about my current exercise set. can i post on this topic? I'll better read on the forum rules;

the a that satisfies the condition is a= -b -c -d. So the three possible matrices are: \left(\begin{array}{cc} 1 & a\\ 0 & 0 \end{array}\right), \left(\begin{array}{cc} 0 & 0\\ 1 & a \end{array}\right) and \left(\begin{array}{cc} 0 & 0\\ 0 & 0 \end{array}\right) is that correct?

oh, how I've missed this... so there are many row-reduced matrices like that... but how i will find the three matrices that satisfies the condition?

so.. the row reduced definition provided by the book is given as follows: An mxn matrix R is called row-reduced if: a) the first non-zero entry in each non-zero row of R is equal to 1; b) each column of R which contains the leading non zero entry of some row has all its other entries...

Let A = [a b; c d] a 2x2 matrix with complex entries. Suppose that A is row-reduced and also that a+b+c+d =0 . Prove that there are exactly three such matrices... so i realize that there are seven possible 2x2 matrices that are row-reduced. [1 0; 0 1], [0 1; 1 0], [0 0; 1 0], [0 0;0 1]...

where is "below" interpret as "above" ^^

exists other book, whose writer is mrs. Leon Chua (the father of memristor), called "Computer-Aided Analysis of Electronic Circuits: Algorithms and Computational Techniques", released on 1975, which is another very good one.Beyond this two books cited below, i didn't find another books about it.

Hello everyone! I'm a brazilian electrical engineer student and enthusiastic on development of circuit simulators, with a approach on the DC-analysis and Transient analysis. now I'm using one book released this year by "wiley and sons", it is a very good one, called "Circuit simulation - Farid...