calc

Yet another CLI calculator. Inspired by the excellent https://github.com/alfredxing/calc.

Installation

With a Rust toolchain in place:

cargo install --force calc

Alternately, you can download a precompiled executable of the most recent release.

Usage

Expression Mode

$ calc "1/(2+(3*(4-5)))"
-1
$ calc "round(12345 / 543)"
23

When non-flag arguments are present, calc interprets them as an expression and evaluates them immediately.

Shell Mode

$ calc
[0]: 1 + 1
2
[1]: 3*(5/(3-4))
-15
[2]: 3*pi**2
29.608813203268074
[3]: @+1
30.608813203268074
[4]: @@@*2
-30
[5]: ln(-1)
NaN

In the absence of non-flag arguments, calc launches a simple shell which just evaluates each line of input.

Reference

Data Types

Every invocation of calc interprets all arguments as a single data type. By default, calc uses f64, but other data types can be chosen by command-line flag:

• f64 (default): signed 64-bit floating point operations
• u64: unsigned 64-bit integer operations
• i64: signed 64-bit integer operations

Note that the data type chosen will restrict the available operators, functions, and constants. For example, trigonometric operations are not available on integers, and bit-shifting operations are not available on floats.

Numeric Input Format

Numbers may contain _ characters at any point. Those symbols are ignored; they are for user convenience and readability only.

calc can handle inputs in several numeric bases.

• Un-annotated numbers are assumed to be base 10. Example: 123.45.

  Note: this is the only format which is legal for non-integral numbers.

• Numbers with a 0b prefix are in base 2. Example: 0b0110_1010.

• Numbers with a 0o prefix are in base 8. Example: 0o755.

  Note: a leading 0 is not in itself an octal prefix. Example: 0755 equals 0d755.

• Numbers with a 0d prefix are in base 10. Example: 1234_5678.

• Numbers with a 0x prefix are in base 16. Example: 0xdead_beef.

It is legal to intermix inputs of varying bases.

Numeric Output Format

The output format of an expression can be specified by adding a : symbol followed by a format specifier to the expression.

The format specifier can be anything recognized by the num-runtime-fmt crate.

$ calc -u "0o644 | 0o111 :#o"
0o755
$ calc -u '0o755 & !0o111 :04o'
0644

[0]: 0xab :b 4
1010 1011
[1]: @[0] >>> 4 :x_4
b000_0000_0000_000a
[2]: @ & 0xF :4b
1010

$ calc pi / 3 :v#04.4
0d01.0471

Order of Operations

The following order of operations is used to resolve expressions:

• Parentheses ((...))
• Unary Prefix Operators (- !)
• Shifts and Exponentiation (<< >> <<< >>> **)
• Bitwise operations (& | ^)
• Multiplication and Division (* / // %)
• Addition and Subtraction (+ -)

Operations at the same level of precedence are resolved from left to right.

Unary Prefix Operators

• -: Negation
• !: Bitwise Not

Infix Operators

• +: Addition
• -: Subtraction
• *: Multiplication
• /: Division
• //: Truncating Division: divides, truncating all data after the decimal point.
• **: Exponentiation
• % : Arithmetic remainder
• <<: Left Shift
• >>: Right Shift
• <<<: Wrapping Left Shift (Rotate Left)
• >>>: Wrappping Right Shift (Rotate Right)
• &: Bitwise And
• |: Bitwise Or
• ^: Bitwise Xor

Functions

• abs: Absolute Value
• ceil: Smallest integer greater than or equal to the input
• floor: Greatest integer less than or equal to the input
• round: Nearest integer to the input; halfway cases away from 0.0
• sin: Sine
• cos: Cosine
• tan: Tangent
• sinh: Hyperbolic Sine
• cosh: Hyperbolic Cosine
• tanh: Hyperbolic Tangent
• asin: Arcine
• acos: Arccosine
• atan: Arctangent
• asinh: Inverse Hyperbolic Sine
• acosh: Inverse Hyperbolic Cosine
• atanh: Inverse Hyperbolic Tangent
• rad: Convert a number in degrees to radians
• dec: Convert a number in radians to degrees
• sqrt: Square Root
• cbrt: Cube Root
• log: Base-10 Logarithm
• lg: Base-2 Logarithm
• ln: Natural (Base-e) Logarithm
• exp: e**x

Trigonometric functions operate on radians.

Constants

• e: Euler's Number
• pi: Archimedes' Constant
• π: Archimedes' Constant

History

In shell mode, calc keeps the results of all expressions in memory until it is quit.

The pseudovariable @ always refers to the result of the previous expression. The pseudovariable @@ always refers to the result of the expression before the previous. Any number of @ symbols can be chained this way.

Simply chaining @ symbols can get cumbersome. The syntax @{N}, where N is an integer, refers to the Nth previous result. @{1} always refers to the result of the previous expression; it is equivalent to @. @{3} refers to the result 3 expressions ago; it is equivalent to @@@.

The pseuaovariable @[0] always refers to the result of the first expression in this shell session. Likewise, @[1] refers to the second, and so on. The shell interface indicates the current expression.

Warnings

No Implicit Multiplication

Implicit multiplication is not supported. Use a multiplication operator such as *.

Floating Point Errors

Floating point operations can compound lossily, and calc makes no special efforts to guard against this kind of error. For example:

$ calc 'sin(rad(45)) - (sqrt(2) / 2)'
-0.00000000000000011102230246251565

Crate Structure

This crate includes both library code and CLI code. The CLI code is all gated behind feature cli; the cli feature is in the default features. This means that the CLI is built by default. However, it is possible to use this crate as a library without building any of the CLI code by including in your Cargo.toml:

[dependencies]
calc = { version = "*", default-features = false }