HP 33s User Manual
Page 212
14–2
Solving and Integrating Programs
2.
Include an INPUT instruction for each variable, including the unknown. INPUT
instructions enable you to solve for any variable in a multi–variable function.
INPUT for the unknown is ignored by the calculator, so you need to write only
one program that contains a separate INPUT instruction for every variable
(including the unknown).
If you include no INPUT instructions, the program uses the values stored in the
variables or entered at equation prompts.
3.
Enter the instructions to evaluate the function.
A function programmed as a multi–line RPN or ALG sequence must be in
the form of an expression that goes to zero at the solution. If your equation
is f(x) = g(x), your program should calculate f(x) – g(x). "=0" is implied.
A function programmed as an equation can be any type of equation —
equality, assignment, or expression. The equation is evaluated by the
program, and its value goes to zero at the solution. If you want the
equation to prompt for variable values instead of including INPUT
instructions, make sure flag 11 is set.
4.
End the program with a RTN. Program execution should end with the value of
the function in the X–register.
If the program contains a VIEW or STOP instruction, or a message for display (an
equation with Flag 10 set), then the instruction is normally executed only once - it is
not executed each time the program is called by SOLVE. However, if VIEW or a
message is followed by PSE, then the value or message will be displayed for one
second each time the program is called. (STOP followed by PSE is ignored.)
SOLVE works only with real numbers. However, if you have a complex–valued
function that can be written to isolate its real and imaginary parts, SOLVE can solve
for the parts separately.
Example:
Program Using ALG.
Write a program using ALG operations that solves for any unknown in the
equation for the "Ideal Gas Law." The equation is:
P x V= N x R x T
where
P = Pressure (atmospheres or N/m
2
).
V = Volume (liters).
N = Number of moles of gas.