refactor: make sparse solver test work

data/tetests/spsolve_test.txt

-g = [x1+3/3 * x2+ min(2,5)*x3 - 1 = 0, 1*3*x2 - 4*3 = 0, 1*3 * x2+sin(8-2)*x3 - 7 = 0];
-r = sp_linsolvex(g, [x1,x2,x3]);
+g1 = x1+3/3 * x2+ min(2,5)*x3 - 1;
+g2 = 1*3*x2 - 4*3;
+g3 = 1*3 * x2+sin(8-2)*x3 - 7;
+b = [0,0,0];
+r = sp_linsolvex([g1,g2,g3], b, [0,0,0], [x1,x2,x3]);
 return r;
\ No newline at end of file