$title 'Test invert utility' (INVERT01,SEQ=391) $ontext Test the invert utility: 1. write a square matrix to a GDX file 2. call 'invert' (an external program) to do the inversion 3. read in the invert from a second GDX file 4. test that A * A-inv = I Contributor: Erwin Kalvelagen and Steve Dirkse, July 2008. $offtext * Introduce a set that leaves holes in the uel sequence of i and does not start at 1 set offset / x1*x5,i1,x6*x10,i2,x11*x15,i3,x16*x20/; set i /i1*i3 /; alias (i,j,k); table a(i,j) 'original matrix' i1 i2 i3 i1 1 2 3 i2 1 3 4 i3 1 4 3 ; parameter inva(i,j) 'inverse of a' chk(i,j) 'check the product a * inva' ; execute_unload 'a.gdx',i,a; executeTool.checkErrorLevel 'linalg.invert i a inva -gdxIn=a.gdx -gdxOut=b.gdx'; execute_load 'b.gdx',inva; chk(i,j) = sum{k, a(i,k)*inva(k,j)}; chk(i,j) = round(chk(i,j),15); display a,inva,chk; chk(i,i) = chk(i,i) - 1; abort$[card(chk)] 'a * ainv <> identity'; executeTool.checkErrorLevel 'linalg.invert i a inva'; chk(i,j) = sum{k, a(i,k)*inva(k,j)}; chk(i,j) = round(chk(i,j),15); display a,inva,chk; chk(i,i) = chk(i,i) - 1; abort$[card(chk)] 'a * ainv <> identity';