Once again, we will use the file
``basefile.m''.
The second file that we use in this step is nearly identical to the
one we used in
part 1
of problem B.
The file is called
problem2.step2.m.
The only difference between this file and
problem2.m,
which we used in step 1 is the additional relations
which set P13 and its transpose
P31 to zero.
In this step the NCProcess command creates a spreadsheet
file called
``Banswer2.dvi''.
Once again we have quite a few more relations than we actually care
to look at. All that we need to do is find some categories which
allow us to make some progress. As long as we can gain some
additional knowledge, we can feed it back into the computer and let
the computer do the work.
It turns out that there are at least three interesting categories in
this spreadsheet. The first one tells us something about
P33.
The expressions with unknown variables
and knowns
The first equations tells us that
P33 acts like 2 on the range of
B2.
The remaining equations in this category give many independent
constraints satisfied by
P33 equals 2.
This motivates the assumption
that P33 is, in fact, 2 times the identity matrix.
The following category is very similar. By the same analysis we can
assume that that the inverse of
P33 is 1/2 times the identity.
This also supports our assumption about
P33 itself.
The expressions with unknown variables
and knowns
Using our assumtion about
P33, the following category allows us to solve
for
P23.
The expressions with unknown variables
and knowns
If we manually substitute for
P33, we can see that
P23 is zero.
This category is analogious to the
category in step 1 that allowed us to
assume P13 was zero.
At this point we could analyze the spreadsheet further, but since we
have made significant progress we will make the assumptions that we
have noted here and move on to
step 3.