Verifying
the
Result
After the
SOLVE
calculation ends, you can verify that the result is
indeed a root of
f(x)
by reviewing the values left in the stack:
• The display (the
X-register)
and the
variable
itselfcontain the solu
tion (root)for the unknown; that is, the value that makes
f(x)
= 0.
• The Y-register (press
I"rT1
to view Y)contains the previous estimate
for
the
root.
This
number
should
be
the
same
as
the
value
in
the
X-
register.
If it is
not,
then the root
given
was only an
approximation
to the root,
and
the values in the X-
and
Y-register bracket the root.
These bracketing numbers should be
close
together.
• The
Z-register
(press
dE)
again
to
view
Z)
contains
the
value
of
f(x)
at the
value
given
in the
X-register.
For
an
exact
root, this should
be zero. If it is not zero, then the root given was only an
approxima
tion,
and
this
number
should
be
close to zero.
If a calculation
ends
with
NO
ROOT
FND, this
means
that
the
cal
culation couldnot
converge
on a root, so the
values
in the
X-
and
Y-
registers
are
probably
not
close
together.
(You
canseethe
value
in the
X-register—the
final
estimate
of the
root—by
pressing
[51
or
RTI
to
clearthe
message.)
These
two
values
bracket the interval that was last
searched for the root. The Z-register contains the value of
f(x)
at the
final
estimate
of
the
root.
This
value
should
not
be
close
to
zero.
Interrupting
the
SOLVE
Calculation
To
halt the
calculation,
press
[c] or[rTs]. Thecurrent best
estimate
of
the
root is
in
the
unknown
variable; use Hi view I to view it without
disturbing the
stack.
To
resume
the calculation, pressIR/s
I.*
• Pressingfxiol,
fGTQl,
or {RTN}
cancels
the
SOLVE
operation.
In this
case,
start
the
pro
gram over rather than resuming it.
7:
Solving
for
an
Unknown
Variable
in
an
Equation
119
To Next Page
Loading...
