nRPNc

Reverse Polish Notation calculator written in Nim.

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Usage:

This calculator uses reverse polish notation to enter and calculate values, meaning the operation is entered after the values, like so:

1 1 +
= 2

What happens here, is the first two entries, being numbers, are pushed into the stack, and then the operator pops the top two numbers off the stack, calculates them together(in this example, they're added), and pushes the result back onto the stack(and since the last item of the input is an operation, the result is also printed, following the =).

Because of this, multiple operations can be chained together:

1 1 + 4 *
= 8

Many people may be used to RPN calculators that have an enter button to input numbers, or may want to use a number pad one-handed for calculations, rather than relying on the spacebar. This calculator allows such a method by pressing the enter key after each entry:

1
1
+
= 2

Operators:

Standard operators:

The following operators are supported:

• + addition

• - subtraction

• * multiplication

• / division

• % modulus/remainder

• ^ exponent

Variadic operators:

NRPNC also has variants to do cumulative operations to the whole stack:

• ++ sums the whole stack together

• -- subtracts the whole stack together

• ** multiplies the whole stack together

• // divides the whole stack together

There are also operations that can be applied over each item in the stack:

• %... removes the top item from the stack and uses it to apply a modulus operation to each item in the stack.

• ^... removes the top item from the stack and raises every item in the stack to that power.

Comparison operators:

Comparison operations are also supported. They pop the top two numbers off of the stack, compare them, and push either a 0 for false or 1 for true back in:

• < less than

• > more than

• == equal to

• != not equal to

• <= less than or equal to

• >= more than or equal to

Built-in functions:

The following functions are supported:

• abs absolute value

• atan arctangent

• atan2 arctangent from two arguments

• atanh hyperbolic arctangent

• cbrt

• ceil round a number with decimal up to the next integer

• cos cosine

• cot cotangent

• csc cosecant

• d2r convert degrees to radians

• exp raise second item down on the stack to power of top item of the stack

• fac factorial

• flr round a number with decimal down to the previous integer

• gam gamma

• gcd greatest common denominator between two arguments

• hyp hopotenuse of two arguments

• sec secant

• sin sine

• sqrt square root

• tan tangent

Stack Manipulation functions:

• ds dump the stack, emptying it

• dup duplicates the top element of the stack

• pop pop the top element off the stack

• pop@ pop the element indicated by the top item of the stack from the stack

• sto: pops the top value from the stack and stores it in the variable declared following the sto: command.

Miscelaneous functions:

• clr clear screen

• quit exits the calculator

Control flow:

if/else statements are supported and allow for nested if/else statements:

• if checks the top value of the stack. If zero, it moves the program forward until it finds an else of fi statement. If non-zero, the entries following it are executed.

• else denotes the start of a code block to be executed if a false value is encountered by a preceeding if statement.

• fi closes an if/else statement

Users can also declare their own functions. Functions are delimted with { and }. You can delcare a function in the following syntax:

{ <function_name_here> <function body here> }

Functions are able to call functions declared within them, in the same scope as them, or in a parent scope.