255
T
T
h
h
e
e
‘
‘
S
S
y
y
m
m
b
b
o
o
l
l
i
i
c
c
’
’
g
g
r
r
o
o
u
u
p
p
o
o
f
f
f
f
u
u
n
n
c
c
t
t
i
i
o
o
n
n
s
s
The = ‘function’
Although this is listed in the
MATH
menu as if it were a function, it is not really.
Except in programming, the = sign is simply used in exactly the way that you
would expect it to be, mainly in the Solve aplet. It’s easier to obtain the = sign
directly from the keyboard.
ISOLATE(expression,var-name)
This function will rearrange a formula so that its subject is another variable.
To do this, the formula must be rewritten so that it is an expression which
equals zero. The
ISOLATE
function then rearranges the formula in terms of
that variable.
Eg. 1 Rewrite the formula
2
1
2
d
at
=
in ‘t’.
Firstly, rewrite as:
2
1
0
2
d
at
−
=
Use:
ISOLATE(D-AT
2
/2,T)
The result needs interpretation as the answer should be
2
D
T
A
= ±
. Firstly,
the ‘T=’ is missing and secondly, the symbol ‘
S1
’ stands for the
±
sign.
Eg. 2 Make
X
the subject of the formula
(
)
3
B
X
A
−
=
−
.
Using:
ISOLATE(3/(X-A)+B,X)
gives:
3/-B+A
equivalent
to:
3
X
A
B
−
=
+
.
The
ISOLATE
function is very useful within its
limitations, but it will not deal with a lot of
formulae. See right:
See also:
