232 Appendix A: Functions and Instructions
rref() MATH/Matrix menu
rref(
matrix1
[,
tol
]) ⇒
matrix
Returns the reduced row echelon form of
matrix1
.
rref([ë 2,ë 2,0,ë 6;1,ë 1,9,ë 9;
ë 5,2,4,ë 4])
¸
1 0 0 66/71
0 1 0
147
71
0 0 1 ë 62/71
Optionally, any matrix element is treated as zero
if its absolute value is less than
tol
. This tolerance
is used only if the matrix has floating-point
entries and does not contain any symbolic
variables that have not been assigned a value.
Otherwise,
tol
is ignored.
• If you use ¥¸ or set the mode to
Exact/Approx=APPROXIMATE, computations
are done using floating-point arithmetic.
• If
tol
is omitted or not used, the default
tolerance is calculated as:
5Eë 14 ù max(dim(
matrix1
))
ù rowNorm(
matrix1
)
Note: See also ref().
rref([a,b,x;c,d,y]) ¸
1 0
dø x-bø y
aø d-bø c
0 1
ë (cø x-aø y)
aø d-bø c
sec() MATH/Trig menu
sec(
expression1
) ⇒
expression
sec(
list1
) ⇒
list
Returns the secant of
expression1
or returns a list
containing the secants of all elements in
list1
.
Note: The argument is interpreted as either a
degree or radian angle, according to the current
angle mode.
In Degree angle mode:
sec(45) ¸
(2)
sec({1,2.3,4}) ¸
1
cos(1)
1.000…
1
cos(4)
sec
L1
() MATH/Trig menu
sec
L1
(
expression1
) ⇒
expression
sec
L1
(
list1
) ⇒
list
Returns the angle whose secant is
expression1
or
returns a list containing the inverse secants of
each element of
list1
.
Note: The result is interpreted as either a degree
or radian angle, according to the current angle
mode.
In Degree angle mode:
sec
L1
(1) ¸ 0
In Radian angle mode:
sec
L1
({1,2,5}) ¸
0
p
3
cos
L1
(1/5)
sech() MATH/Hyperbolic menu
sech(
expression1
) ⇒
expression
sech(
list1
) ⇒
list
Returns the hyperbolic secant of
expression1
or
returns a list containing the hyperbolic secants of
the
list1
elements.
sech(3) ¸
1
cosh(3)
sech({1,2.3,4}) ¸
1
cosh(1)
.198…
1
cosh(4)
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