Angel wrote:
Why do x<-b%*%ginv(A)
Why should it be the same??? Here, you are calculating (A+ is G-Inverse)
x = b * A+
Let me add: More exactly, you are calculating
x = b' * A+
because b * A+ doesn't fit and R is somehow "intelligent" here and transposes b for you instead of complaining ...
Uwe
and x<-solve(A,b)
Here, you are calculating (A- is Inverse of A)
A * x = b <=> A- * A * x = A- * b <=> x = A- * b
So you have to compare, e.g.:
ginv(A) %*% b solve(A, b)
Uwe Ligges
give different results?. It seems that I am missing some basic feature of matrix indexing. e.g.:
A<-matrix(c(0,-4,4,0),nrow=2,ncol=2) b<-c(-16,0) x<-b%*%ginv(A);x x<-solve(A,b);x
Thanks in advance, Angel
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