Rkfstep; Rlb - HP 48gII Advanced User's Reference Manual

RKFSTEP

Type: Command
Description: Next Solution Step for RKF Command: Computes the next solution step (h
problem for a differential equation.
The arguments and results are as follows:
• { list } contains three items in this order: the independent (t) and solution (y) variables, and
the right-hand side of the differential equation (or a variable where the expression is stored).
• x sets the tolerance value.
tol
• h specifies the initial candidate step.
• h is the next candidate step.
next
The independent and solution variables must have values stored in them. RKFSTEP steps these
variables to the next point upon completion.
Note that the actual step used by RKFSTEP will be less than the input value h if the global error
tolerance is not satisfied by that value. If a stringent global error tolerance forces RKFSTEP to
reduce its stepsize to the point that the Runge–Kutta–Fehlberg methods fails, then RKFSTEP
will use the Euler method to compute the next solution step and will consider the error tolerance
satisfied. The Runge-Kutta-Fehlberg method will fail if the current independent variable is zero
and the stepsize 1.3 × 10
magnitude.
...µ
Access:
Input/Output:
See also: RKF, RKFERR, RRK, RRKSTEP, RSBERR
RL
Type: Command
Description: Rotate Left Command: Rotates a binary integer one bit to the left.
The leftmost bit of #n
... ã
Access:
Flags: Binary Integer Wordsize (-5 through -10), Binary Integer Base (-11, -12)
Input/Output:
See also: RLB, RR, RRB

RLB

Type: Command
Description: Rotate Left Byte Command: Rotates a binary integer one byte to the left.
The leftmost byte of #n
eight times.
... ã L
Access:
Flags: Binary Integer Wordsize (-5 through -10), Binary Integer Base (-11, -12)
3-148 Full Command and Function Reference
or if the variable is nonzero and the stepsize is 1.3 × 10
-498
RKFS
L /A L /A
3 1 2 n
{ list } x
tol
L = Level; A = Argument; I = item
becomes the rightmost bit of #n
1
BIT RL
Level 1/Argument 1
#n
1
becomes the rightmost byte of #n
1
BYTE RLB
L /A L /I
1 n+1 3 1
h { list }
.
2
(ã is the right-shift of the 3key).
. RLB is equivalent to executing RL
2
(ã is the right-shift of the 3key).
) to an initial value
next
times its
-10
L /I L /I
2 2 1 3
x h
tol next
Level 1/Item 1
#n
2