Am 14.09.2021 14:10 schrieb Allin Cottrell:
On Tue, 14 Sep 2021, Riccardo (Jack) Lucchetti wrote:
On Tue, 14 Sep 2021, atecon wrote:
One question: How would such an "end" operator work "under the hood"?
a) Is it triggering the computation of rows(X) AND cols(X) each time
"end" is called, or
b) is it a property of matrix X, meaning that once X is initialized,
the number of rows and columns is automatically computed and this
information stored as a property of the object X?
It's (b). The computational cost of the rows() and cols() function is
nearly zero. The "matrix" struct definition is in
lib/src/gretl_matrix.h, line 77.
Exactly zero, I'd say. In hansl you need to call rows() or cols() to
get the dimensions of a matrix but internally, in C, rows and cols are
members of the matrix struct so no computation is required, just a
read.
Thanks for the clarification.
Best,
Artur
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