(12C) Programming Tricks

10062016, 07:41 PM
Post: #1




(12C) Programming Tricks
http://edspi31415.blogspot.com/2016/10/h...ricks.html
These tricks can help you cut steps in your programming. Remember that it is still important to test results. Happy programming! Using Last X This can be a godsend in making programs more efficient. Unless you are using the Platinum Edition, we only have 99 steps to work with. The LST X function returns the x argument that is last used in a calculation. LSTx Returns: OneArgument Functions: √, LN, e^x, FRAC, INTG, n! The x precalculation TwoArgument Functions (Arithmetic): +, , *, ÷, y^x The x value in the arithmetic operation Number of Inputs I follow a general rule when it comes to the number of inputs required on an HP 12C program. If the number of inputs is 1 or 2, I would have the user enter inputs on the stack and run the program. If the number of inputs is 3 or more, I have the user prestore the inputs into registers before pressing [R/S] to run the program. Example: If my program calls for a, b, and c, I have the user store a in register 0, b in register 1, and c in register 2, and then have the user press [R/S]. Branching You can branch a program to different parts of the program. You designate a register as a choice variable. (Rc = 0 for option 0, 1 for option 1, etc). Examples include setting the variable for computing combinations vs permutations, set for month payments vs yearly payments. See this link for an example: http://edspi31415.blogspot.com/2016/08/h...omial.html Program format: RCL Rc Test value  X=0? GTO (applicable line number) … (applicable section) (commands and calculations) GTO 00 (end the program) Multiply x by 100 Keystroke: [ENTER], 1, [x<>y], [%T] Result: The X stack has 100*x, the Y stack has x. Dividing x by 100 Keystrokes: [ENTER], 1, [ % ] Results: The x stack has x/100, the Y stack has x. Quickly entering numbers in the form of 10^n (n is an integer) Keystrokes: 1, [EEX], n This is useful when n>2. For example, entering 10000 takes five steps normally. With this sequence, 1 [EEX] 5, you only use 3. Another Way to Double Keystrokes: [ENTER], [ + ] Results: X Stack: 2*x. 1 program step saved. Absolute Value of x. Keystrokes: 2, [y^x], [ g ] [ √ ] Result: X Stack: x. It is important to square the number first since the HP 12C’s square root function returns an error on negative numbers. Signum Function of x. This is the extension of the absolute value sequence shown previously. Keystrokes: [ENTER], 2, [y^x], [ g ] ( √ ), [ ÷ ] Result: X Stack: sgn(x) Modulus (for two positive values) Keystrokes: a, [ENTER], b, [ ÷ ], [ g ] (LSTx), [x<>y], [ g ] (FRAC), [ * ] Result: X stack: a MOD b Comparing Values We have a value stored in a register, call it Rc, where c obviously can stand for 0, 1, and so on. Keystrokes: [RCL], c, [  ], [ g ] (x=0) If the test is true (x = Rc), the next step is executed. Otherwise, it is skipped. Six Digit Approximation of π Since the HP 12C does not have a π button, we’ll have to enter a 10 digit approximation of π, which will take 11 steps. However, if you want an approximation (given most of the time the HP 12C is used on Fix 2 mode), we can use the approximation π ≈ 355/113, which is accurate to six decimal places. π ≈ 3.14159265359 355/113 ≈ 3.14159292035 Keystrokes: 355, [ENTER], 113, [ ÷ ] Calculate (1 + n/100)^x without using the TVM Registers Keystrokes: 1, [ENTER], n, [ % ], [ + ], x, [y^x] 

10072016, 12:53 AM
Post: #2




A very handy collection
Thanks a lot for this. Some I have used before. It's handy to have this set in one place.


10072016, 06:43 PM
(This post was last modified: 10072016 06:48 PM by Dieter.)
Post: #3




RE: (12C) Programming Tricks
Eddie, thank you for this collection of useful tips for the 12C and other calculators.
Let me add a few remarks: (10062016 07:41 PM)Eddie W. Shore Wrote: Multiply x by 100 I'd say the Yregister after this procedure is 1, not x. (10062016 07:41 PM)Eddie W. Shore Wrote: Quickly entering numbers in the form of 10^n (n is an integer) Actually only 2. The "1" is not required, a simple [EEX] 5 does it. (10062016 07:41 PM)Eddie W. Shore Wrote: Another Way to Double It depends. In most cases "2 [x]" does it, an initial [ENTER] is not required. So both methods usually take the same two steps. On the other hand the proposed method saves X in LstX which can be helpful. (10062016 07:41 PM)Eddie W. Shore Wrote: Absolute Value of x. Instead of using the power function, [ENTER] [x] usually is faster. This applies to most calculators. (10062016 07:41 PM)Eddie W. Shore Wrote: Signum Function of x. There's one ENTER missing. [ENTER] [ENTER] [x] [g] [√] [÷] Or maybe [ENTER] [ENTER] 2 [x^x] [g] [√] [÷] (10062016 07:41 PM)Eddie W. Shore Wrote: Modulus (for two positive values) This can cause roundoff errors. Better use a mod b = a – b * int(a/b): a [ENTER] [ENTER] b [÷] [g] [LSTx] [x<>y] [g] [INTG] [x] [–] This requires one more stack register (Z) but it returns exact results. Dieter 

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