Biology Reference
In-Depth Information
Exercise 8.16.
a. Complete the remaining four columns of the change-of-basis matrix A
,from
B,P
basis
B
to
P
, using the results of Exercise 8.13 :
1
1
0
0
0
0
A
B , P =
.
0
1
0
0
0
0
T
B
b. Use A
.
Also , what vector of N ( S ) does u represent, expressed in terms of the standard
coordinates in
to find the coordinates of u
:= (
1
,
3
,
0
,
1
,
2
,
1
)
in terms of
P
B , P
11 ?
R
T
B
c. Use A
tofind the coordinates of an arbitrary vector c
:= (
c 1 ,
c 2 ,
c 3 ,
c 4 ,
c 5 ,
c 6 )
B , P
in terms of
P
.
In the next exercise, you will repeat the previous exercise, but switch the roles of
B
.
Exercise 8.17.
and
P
a. Using the results of Exercise 8.15 , now find the change-of-basis matrix A P,B
from basis
P
to basis
B
of N ( S ).
T
P
b. Use A
.
Also , what vector of N ( S ) does v represent, expressed in terms of the standard
coordinates in
to find the coordinates of v
:= (
1
,
3
,
0
,
1
,
2
,
1
)
in terms of
B
P,B
11 ?
R
c. Use A
to find the coordinates of an arbitrary vector d
:= (
d 1 ,
d 2 ,
d 3 ,
d 4 ,
P,B
T
P
.
d. Compute the matrix products A B,P A P,B and A P,B A B,P , and explain your
answer.
d 5 ,
d 6 )
in terms of
B
The “Rank + Nullity Theorem” 10 says that, for an arbitrary matrix
Exercise 8.18.
A
M m , n ( R )
,
dim
(
N
(
A
)) +
rank
(
A
) =
n
,
where the dimension dim
of the nullspace of A is often called the nullity of
A , and rank ( A ), the rank of A , is the dimension of the row space of A , equivalently,
the number of nonzero rows in E A .
Suppose for parts (a) - (d) and (f), S
(
N
(
A
))
M m , n ( R )
is a generic stoichiometric matrix:
a. Recall: What is the biological meaning of the number n of columns of S ?
b. Recall: What is the biological meaning of the number m of rows of S ?
10 This is sometimes just called the “Rank Theorem.”
 
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