1. The problem statement, all variables and given/known data A)Determine the elements of the matrix G such that GY = (Y1 +Y2 + Y3, Y3-Y1, 0.5Y1 - 0.5Y3 +2Y2)' B)Find the unique symmetric matrix A such that Y'AY = Y'GY. Y= [2 7 6] 2. Relevant equations 3. The attempt at a solution I know that Y1=2, Y2=7, and Y3=6. That means the right hand matrix should be Z= [15 4 12] So: GY=Z GYY'=ZY' G=ZY'(YY')^1 Using proc IML in SAS I get something like: 0.3370787 1.1797753 1.011236 0.0898876 0.3146067 0.2696629 0.2696629 0.9438202 0.8089888 However, I was talking to a friend, and he just matched up the coefficients and got G= 1 1 1 -1 0 1 .5 2 -.5 This also makes sense to me, so I don't understand why our numbers would be so different. Did I do something wrong in my equation above? For part B, I did the same thing Y'AY = Y'GY Y'AYY'=Y'GYY' Y'AYY'(YY')^-1 = Y'GYY'(YY')^-1 Y'A=Y'G YY'A=YY'G (YY')^-1YY'A=YY')^-1YY'G A=G However, G is not symmetric (in either case). I'm not sure what else I can do. Thanks in advance for the help.