Hi Richard,
If you copy one of the odd expressions in the matrix A and paste it into a text editor or into this answer form you will see that there is an odd character sequence at the end \.10
-6249.804693603325` (-0.0012229040441303532` - 3.203739988383671`*^-11 \.10)
that is what is preventing the expression from being evaluated. It is the "funny character" that Daniel referred to in the definition of Gkp4j0. It is rendered as a space in the notebook at the end of the definition, so it is not obvious. If you delete it, save the notebook, restart the kernel and evaluate, matrix A no longer has those odd expressions.
(0 0 0 0 0 0 0 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0 1 0 0 0 0 0
0 0 0 0 0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 0 0 0 0 0 1 0 0
0 0 0 0 0 0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 1
-0.043046 7.64291 22.9287 38.2146 53.5004 68.7862 84.072 -0.0549892 0 0 0 0 0 0
-0.0000185048 -0.263621 -0.542812 -0.855948 -1.21272 -1.55219 -1.90131 0.00124263 0 0 0 0 0 0
-6.16827*10^-6 -0.0822449 -0.552241 -0.442067 -0.354635 -0.542812 -0.618047 0.000414211 0 0 0 0 0 0
-3.70096*10^-6 -0.0269271 -0.25784 -1.12948 -0.614954 -0.197584 -0.43756 0.000248527 0 0 0 0 0 0
-2.64354*10^-6 -0.0284048 -0.0256587 -0.496523 -1.99534 -0.902137 -0.0707305 0.000177519 0 0 0 0 0 0
-2.05609*10^-6 -0.0169696 -0.0822449 0.0173475 -0.81441 -3.14982 -1.28589 0.00013807 0 0 0 0 0 0
-1.68225*10^-6 -0.0171755 -0.031871 -0.136097 0.0907671 -1.21611 -4.59291 0.000112967 0 0 0 0 0 0
)
