Re: matrix of coefficients?

*To*: mathgroup at christensen.cybernetics.net*Subject*: Re: matrix of coefficients?*From*: olness at phyvms.physics.smu.edu (Fredrick Olness (214) 768-2500 or -2495, Fax -4095)*Date*: Tue, 25 Oct 1994 11:56:20 -0500

RE: matrix of coefficients? Martin McClain, WRITES: If varsN = a list of N variables, and if exprsN = a list of of N expressions, each one linear in the variables of varsN, Is there some operator (that I haven't found yet), or some clever way to use a nonobvious operator, to get the matrix of coefficients? ====================== If I interpret the question properly, I believe an answer is: varsN=Array[v,3] {v[1], v[2], v[3]} exprsN=Table[Sum[a[i,j] varsN[[i]],{i,3}],{j,3}]; exprsN //TableForm a[1, 1] v[1] + a[2, 1] v[2] + a[3, 1] v[3] a[1, 2] v[1] + a[2, 2] v[2] + a[3, 2] v[3] a[1, 3] v[1] + a[2, 3] v[2] + a[3, 3] v[3] table=Table[ Coefficient[exprsN[[i]],varsN[[j]] ],{i,3},{j,3}]; table //TableForm a[1, 1] a[2, 1] a[3, 1] a[1, 2] a[2, 2] a[3, 2] a[1, 3] a[2, 3] a[3, 3] ====================== Fredrick I. Olness SMU Mail: Department of Physics Fondren Science Bldg. Southern Methodist University Dallas, TX 75275 Phone: (214) 768-2500 (SMU Office) (214) 768-2495 (SMU Secretary) (214) 768-4095 (SMU FAX) Internet: Olness at phyvms.physics.smu.edu (129.119.200.74) Olness at mail.physics.smu.edu