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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
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