MathGroup Archive 1998

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Gaussian Elimination wont work in my example


Cheng L L wrote:
> 
> I have tried to solve a matrix
> 
> {{-4, -2},{-2, -1}]. e =0 where e is a 1x2 matrix say [{a, b}] and
> Tranpose[Conjugate[e]].e =1. I use Guassian Elimanation "LinearSolve"
> to solve this equation, but it all the time gives out {0,0}, the answer
> is not what I want in my case. Please help me to solve this puzzle.
> Many thanks.
> 
> Best regards,
> LL Cheng
> (City University of Hong Kong, EE Dept)
> 
> email : eeacheng at cityu.edu.hk

In[1]:=  m={{-4, -2},{-2, -1}}

Out[1]= {{-4, -2}, {-2, -1}}

In[2]:= Det[m]

Out[2]= 0

=> You have none or an infinity of solutions

In[3]:= e={{a},{b}}

Out[3]= {{a}, {b}}

In[4]:= Map[First[#]==0 &,m.e]

Out[4]= {-4 a - 2 b == 0, -2 a - b == 0}

In[5]:= Solve[%,a] //InputForm

Out[5] //InputForm= {{a -> -b/2}}

Tobias


  • Prev by Date: Re: discrete math, how many zeroes in 125!
  • Next by Date: Back issues of Mathematica Journal plus software
  • Previous by thread: Re: Gaussian Elimination wont work in my example
  • Next by thread: file related trouble (unix)