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# Calculation Methods Used by CALC 1

CALC 1 supports chain (CHN), Reverse Polish Notation (RPN) and algebraic formulas (ALG) calculation methods.

## Chain

Chain mode is the default system for many business and financial calculators. Good for basic to moderate calculations since each operation is executed immediately. Undo is available for every operation to make it easy to recover from mistakes.

2+3×4 = 20.00. 5.00 will be displayed after tapping ×.
Use parenthesis for, 2+(3×4 = 14.00

498+7% will display 498.00+34.68 after tapping the % key. 532.86 will be displayed after tapping =.

See Calculations Using the Chain (CHN) Calculation Mode for examples of the chain method.

## Reverse Polish Notation

Reverse Polish Notation (RPN) is used on many HP scientific and financial calculators. It is an efficient, parenthesis free system. Undo is available for every operation to make it easy to recover from mistakes.

2+3×4 can equal 20 or 14 depending on how the user enters the values and operators.
2 ENTER 3 + 4 × will equal 20.00
2 ENTER 3 ENTER 4 × + will equal 14.00

For percentages, 498, ENTER, 7 % will display 34.68. Then tapping + will display 532.86.

See Calculations Using RPN and the Stack for examples of the RPN method.

## Algebraic

The CALC 1 algebraic mode is similar to formulas in spreadsheets and scientific calculators. It is good for difficult calculations.

The formula is in a separate area than the results so you can view the entire formula that produced the results. The entire formula is executed when you tap "=". This is good that you can view the entire formula but the disadvantage over chain and RPN is that undo is not available for every operation.

For the algebraic method, CALC 1 uses the same standard order of operation that spreadsheets and computer languages use in evaluating expressions.

2+3*4 = 14.00
(2+3)*4 = 20.00

CALC 1 also supports the % operator in ALG mode:

498+7% = 532.86

Algebraic calculation mode is good for formulas like:
1/(1+10^(-(1856-1716)/400)) = 0.6912 (Elo Expected Score)

See Calculations Using Algebraic Formulas for examples of the algebraic method.

Algebraic formulas are used to power the CALC 1 keys (Key Editor) and Formula Calculators (Formula Calculator Editor).

## Functions in Algebraic Calculation Mode

CALC 1 is compatible with popular spreadsheet functions. We use the same name and arguments used in spreadsheets so you do not need to learn a new system. This will also make it easier to copy formulas from spreadsheets you use to a CALC 1 key or Formula Calculator.

A CALC 1 function that uses a list will use listx, listy or listf for functions like AVERAGE() and SUM() instead of a cell range like A1:A5.

CALC 1 also uses a few C math (math.h) functions that are not available in spreadsheets like CBRT() for cube root.

CALC 1 uses the math.h namespace convention for the naming of common mathematical constants, but without the underscore. So the value of pi is mpi and 1/pi is m1pi. The underscores were left out since CALC 1 was designed for iOS and the underscore was two keyboards away from the "ABC" keyboard.