Re: [Gretl-devel] Dealing with big(!) matrix

On Sun, 28 May 2017, Marcin Błażejowski wrote: It turns out, there's a huge difference when matrices are smaller (and besides, memory allocation costs are reduced to the bare minimum. Try this: <hansl> set verbose off function scalar find_0(const matrix a, scalar column, scalar target) n = rows(a) c = a[,column] .= target c = selifr(seq(1,n)'~a, c) return c[1,1] end function function scalar find_1(const matrix a, scalar column, scalar target) #n = rows(a) chk = 0 i = 1 loop while !chk --quiet chk = a[i++,column] == target endloop return i-1 end function function scalar find_2(const matrix a, scalar column, scalar target) n = rows(a) loop for i=1..n --quiet if (a[i,column] == target) index = i break endif endloop return index end function n = 6000 a = mrandgen(i,1,1000,n,2) target = 365 column = 1 rep = 5000 set stopwatch loop rep find_0(a, column, target) endloop t0 = $stopwatch loop rep find_1(a, column, target) endloop t1 = $stopwatch loop rep find_2(a, column, target) endloop t2 = $stopwatch print t0 t1 t2 </hansl> ------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti -------------------------------------------------------