calculator

calculator in rust

Derived From https://github.com/asmoaesl/rsc

RSC is a handwritten scientific calculator for turning an equation inside a string into a result.

The abbreviation can be interpreted in two majorly different ways:

• Rust Scientific Calculations library
• Rust Scientific Calculator

Installation

First, you should nstall rustup, cargo, rustc, etc. for basic rust development.

Compile from Source Using Cargo

You can access option information by starting RSC with the option "help", such as: cargo run -- help OR just try with AST cargo run -- ast OR just try cargo run

Use

RSC will open to a single input dialog with an arrow pointing to the right. Here you just enter a mathematical expression and it will attempt to calculate it and print the result. The expression can include spaces.

>2 + 2
4
>3(3)
9
>sqrt 4
2
>2+3*4
14
>2+3(4)
14
>(3)(4)
12
>sqrt 4
2
>sqrt(4)
2
>sqrt 4 + 2
4
>sin(6.5/9.7)
0.6210667900937665
>sin cos tan 2
-0.5449592372801408

Similarly, you can exit RSC by entering "exit" or "quit" at the dialog. RSC can be run with the ast flag and show the internal expression that was created by the parser. This is most commonly used for entertainment purposes 😛.

cargo run -- ast
>pi*2^2
BinOp(
    Star,
    Constant(
        3.141592653589793
    ),
    Pow(
        Constant(
            2.0
        ),
        Constant(
            2.0
        )
    )
)
12.566370614359172

Errors

cargo run
>oops
Lexer error: InvalidIdentifier("oops")
>3.3.1
Lexer error: InvalidNumber("3.3.1")
>2+
Parser error: ExpectedFactor(None)
>2(3
Parser error: ExpectedClosingParenthesis

syntax accepted for mathematical expressions in RSC.

Numbers

RSC is pretty lenient when it comes to a number and how you represent it. For example, -0.1 is the same as -.1.

The following is a list of accepted examples of numbers.

• 2
• 256
• -256
• .451
• -.451

The above is valid, but the following is not.

• -.
• 2.1.3
• 2.

Exponentials

RSC supports exponentials using the caret (^). You can enter any term, to the power of, any term.

Expressions like 2^3 and 3+2^3 work as you expect them to. But the expression 2^2+1 probably doesn't do what you think it does. For example:

>2^3
8
>2^2+1
5

You can also chain exponentials together: 2^2^(1+1), which is interpreted as (2^2)^(1+1).

Constants & Functions

Available Constants & Functions

Constants	Functions
E	SQRT
PI	SIN
	COS
	TAN
	LOG

Constants and functions can be in any case you choose, be it uppercase, lowercase, or mixed case.

Constants in Expressions

A constant is interpreted as an ordinary number. For example, when you enter pi, it is just placing the value of PI at that exact location. Expressions like 3pi are not valid, and are read as 3 and 3.14159.... Instead, use 3(pi) or similar.

Functions in Expressions

A function takes the next term immediately following as its operand. For example, sqrt 2, sqrt (2), and sqrt(1+1) are all the same; though sqrt 1+1 is interpreted as sqrt(1) + 1. This makes using the functions simpler. You can say sin cos tan 2 instead of sin(cos(tan(2))).

Precedence

Precedence in RSC is a little weird. The following table can explain more than I ever could in words.

Operation	first:last; 0:4
Functions, Constants, Numbers	0
Parenthesis	1
Exponents	2
Multiplication & Division	3
Addition & Subtraction	4

Two things to note:

1. Functions and constants are considered to be terms themselves.
2. Multiplication & division, like addition & subtraction, are on the same level. 2/3*4 calculates the 2/3 first, not the 3*4. Same with 2-3+4. The reason for this is because most people wouldn't trust the calculator this much and just put parenthesis like 2/(3*4) instead, and secondly, because it would be another hundred lines of code to solve and complicate the code further. Fork if it matters to you. Sorry for any inconveniences.

License

RSC is MIT licensed. RSC will always remain free to modify and use without attribution.