MathU™ RPN 2.2 for iPhone
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Stack And Register Functions

MathU RPN has 20 registers -- 10 primary registers and 10 secondary registers. The registers are shared in that they can be used to store your own values but they are also used by some of the functions on the calculator. Namely, all 20 storage registers may be used to store up to 20 cash flows and some of the secondary registers are used to store values for the statistical functions (see picture below). MathU RPN also has five additional registers dedicated to the financial functions N, i, PV, PMT and FV.

To safely store values in the registers while still performing cash flow analysis, store your values in the uppermost registers. The cash flow functions use registers 0-n where n is the number of cash flows. All registers greater than n will be available.

To safely store values in the registers while still accumulating statistical sums, store your values in the registers 0-10 and 17-19. This avoids the registers shared with the statistics functions.

The 10 primary registers are accessed by pressing STO or RCL followed by the register number 0 through 9. To access the secondary registers (registers 10 through 19) press STO . followed by the register number 0 through 9. The financial registers are accessed by pressing STO or RCL followed by the financial function (N, i, PV, PMT or FV).

 

Key	Function	Description	Stack effect
STO n	sto	Store into register n. Specify . n to access the secondary register (register 10+n)
STO fn	sto	Store into financial register. fn can be N, i, PMT, PV or FV.
STO + n	sto	Add contents of x register to register n
STO − n	sto	Subtract contents of x register from register n
STO × n	sto	Multiply register n with contents of x register
STO ÷ n	sto	Divide register n by contents of x register
RCL n	rcl	Recall from register n. Specify . n to access the secondary register (register 10+n)
RCL fn	rcl	Recall financial register. fn can be N, i,PMT,PV, FV, CF0, CFj or Nj. When fn is CFj, the number periods N is decremented as well so that the next RCL CFj operates on the previous cash flow.
RCL Σ+	rcl	Recall statistics sums.
CLREG	clreg	Clear all registers
x<>y	x<>y	Exchange x and y registers
LST Χ	lastx	Recall last x value
CLX	clx	Clear x register
CLSTK	clstk	Clear stack
R↑	rollup	Rotate stack contents up
R↓	rolldown	Rotate stack contents down
ENTER	enter	Push current value onto stack.
	undo	When entering a number undo the last character, otherwise clear the x register the same as clx.

Repeated Calculations

When a binary computation is performed that causes the stack to drop, the topmost register is automatically replicated. You can take advantage of this behavior to do repeated calculations. It works with either the 16 or 4 high stack but is probably easier to take advantage of with a stack height of 4 (see preferences for how to switch between the two).

To perform a repeated calculation, load the stack completely with the common value and then enter the first value and apply the operand. Press the operand again to compute the next number in the series. Repeat for each number in the series.

Example: To generate a series of numbers that differ by 3,

1. load the stack with the number three:
2. 3 ENTER ENTER ENTER

   (for the 16 high stack case you would need 15 ENTER steps).

3. Enter the starting number (say 2 in this case) and apply the operand +

   2 + ans: 5

4. + ans: 8
5. + ans: 11
6. + ans: 14
7. etc.

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