Texas Instruments TI-89 Manual Book page 440

cos()
TI-89: 2 X key
cos(expression1)
cos(list1)
cos(expression1)
argument as an expression.
cos(list1)
elements in
Note: The argument is interpreted as either a
degree or radian angle, according to the
current angle mode setting. You can use
ó or ô to override the angle mode
temporarily.
cos(squareMatrix1)
Returns the matrix cosine of
This is not the same as calculating the cosine
of each element.
When a scalar function f(A) operates on
squareMatrix1
the algorithm:
1. Compute the eigenvalues (l
eigenvectors (V
squareMatrix1
Also, it cannot have symbolic variables
that have not been assigned a value.
2. Form the matrices:
l
0 l
B =
0 0 ... 0
0 0 ... l
3. Then A = X B Xê and f(A) = X f(B) Xê. For
example, cos(A) = X cos(B) Xê where:
cos (B) =
All computations are performed using
floating-point arithmetic.
TI-92 Plus: X key
expression
list
returns the cosine of the
returns a list of the cosines of all
.
list1
squareMatrix
squareMatrix1
(A), the result is calculated by
) and
i
) of A.
i
must be diagonalizable.
0 ... 0
1
... 0
2
and X = [V ,V
1
n
K
cos( ) 0
1
K
0 cos( )
2
K
0 0
K
0 0
In Degree angle mode:
cos((p/4)ô ) ¸
cos(45) ¸
cos({0,60,90}) ¸ {1
In Radian angle mode:
cos(p/4) ¸
cos(45¡) ¸
In Radian angle mode:
cos([1,5,3;4,2,1;6,ë 2,1]) ¸
.
, ... ,V ]
2 n
0
0
0
cos( )
n
Appendix A: Functions and Instructions
1/2
.212... .205... .121...
.160... .259... .037...
ë.090...
.248... .218...
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2
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2
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‡2
2
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