
From:  marco atzeri 
Subject:  Re: Successive OverRelaxation ... what is wrong? Improvements? 
Date:  Tue, 06 Nov 2012 17:36:33 +0100 
Useragent:  Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 
On 11/6/2012 4:54 PM, Joza wrote:
Thanks for the info...stuff to think about! Besides all this, is there any neat ways to speed out plain old FOR loops using vectors? For example, the ones I have below: for i=1:n sum = 0.0; if i==1 for j=1:2 sum = sum + A(i,j)*x(j); end elseif i==n for j=n1:n sum = sum + A(i,j)*x(j); end else for j=i1:i+1 sum = sum + A(i,j)*x(j); end end
what about multiplication of sparse matrix and vector ? assuming A sparse (n*n) with just 2 or 3 notzero elements per row and x vector (n*1) my_sum=sum(A*x) Regards Marco
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