Re: [Gretl-users] removing nan and inf from a matrix
On Tue, 23 Jul 2013, Logan Kelly wrote:
I need to take the log difference of a matrix, i.e. log(M[2
rows(M):,]/M[1:rows(M)-1,]). Unfortunately, M has elements
equal to zero. I need to replace the nan's and inf's with
0's. This almost works
M = isnan(M) ? 0 : M
but does not remove inf's. Any sugestions?
Is this calculation actually legit? Assuming it is, then
<hansl>
matrix M = muniform(15,2)
M[2,2] = 0
M[3,2] = 0
matrix ldM = log(M[2:rows(M),] - M[1:rows(M)-1,])
ldM = isnan(0 * ldM) ? 0 : ldM
print M ldM
</hansl>
This relies on the IEEE 754 rules: both 0*inf and 0*(-inf)
return nan.
Allin Cottrell