A high precision scientific calculator with full support for physical units.
Try the web version here: https://insect.sh
Contents
Documentation

Evaluate mathematical expressions:
1920/16*9 2^32 sqrt(1.4^2 + 1.5^2) * cos(pi/3)^2

Operators: addition (
+
), subtraction (
), multiplication (*
,·
,×
), division (/
,÷
,per
), exponentiation (^
,**
). Full list: see Reference below. 
Mathematical functions:
abs
,acos
,acosh
,asin
,asinh
,atan
,atan2
,atanh
,ceil
,cos
,cosh
,exp
,floor
,fromCelsius
,fromFahrenheit
,gamma
,ln
,log
,log10
,maximum
,minimum
,mean
,round
,sin
,sinh
,sqrt
,tan
,tanh
,toCelsius
,toFahrenheit
. 
Highprecision numeric type with 30 significant digits that can handle very large (or small) exponents like 10^(10^10).

Exponential notation:
6.022e23
.


Physical units: parsing and handling, including metric prefixes:
2 min + 30 s 40 kg * 9.8 m/s^2 * 150 cm sin(30°)

Supported units: see Reference section below.

Implicit conversions:
15 km/h * 30 min
evaluates to7.5 km
. 
Useful error messages:
> 2 watts + 4 newton meter Conversion error: Cannot convert unit N·m (base units: kg·m²·s⁻²) to unit W (base units: kg·m²·s⁻³)


Explicit unit conversions: the
>
conversion operator (aliases:→
,➞
,to
):60 mph > m/s 500 km/day > km/h 1 mrad > degree 52 weeks > days 5 in + 2 ft > cm atan(30 cm / 2 m) > degree 6 Mbit/s * 1.5 h > GB

Variable assignments:
Example: mass of the earth
r = 6000km vol = 4/3 * pi * r^3 density = 5 g/cm^3 vol * density > kg
Example: oscillation period of a pendulum
len = 20 cm 2pi*sqrt(len/g0) > ms

Predefined constants (type
list
to see them all): speed of light (c
), Planck's constant (h_bar
), electron mass (electronMass
), elementary charge (elementaryCharge
), magnetic constant (µ0
), electric constant (eps0
), Bohr magneton (µ_B
), Avogadro's constant (N_A
), Boltzmann constant (k_B
), gravitational acceleration (g0
), ideal gas constant (R
), ... 
Last result: you can use
ans
(answer) to refer to the result of the last calculation.


Userdefined functions:
Example: kinetic energy
kineticEnergy(mass, speed) = 0.5 * mass * speed^2 > kJ kineticEnergy(800 kg, 120 km/h)
Example: barometric formula
P0 = 1 atm T0 = fromCelsius(15) tempGradient = 0.65 K / 100 m pressure(height) = P0 * (1  tempGradient * height / T0)^5.255 > hPa pressure(1500 m)

Sums and products:
Syntax:
sum(<expression>, <indexvariable>, <from>, <to>) product(<expression>, <indexvariable>, <from>, <to>)
Examples:
# sum of the first ten squares sum(k^2, k, 1, 10) # the factorial of n as the product 1 × 2 × ... × n myFactorial(n) = product(k, k, 1, n)

Unicode support:
λ = 2 × 300 µm ν = c/λ → GHz

And more: tab completion, command history (arrow keys,
Ctrl
+R
), pretty printing, syntax highlighting, ...
Reference

Operators (ordered by precedence: high to low)
Operator Syntax factorial !
square, cube, ... ²
,³
,⁻¹
, ...exponentiation ^
,**
multiplication (implicit) whitespace modulo %
division per
division /
,÷
multiplication (explicit) *
,·
,×
subtraction 
addition +
unit conversion >
,→
,➞
,to
assignment =
Note that implicit multiplication has a higher precedence than division, i.e.
50 cm / 2 m
will be parsed as50 cm / (2 m)
. 
Commands
Command Syntax help text help
,?
list of variables list
,ls
,ll
reset environment reset
clear screen clear
,cls
quit (CLI) quit
,exit

Supported units (remember that you can use tab completion).
All SIaccepted units support metric prefixes. In addition, binary prefixes (
MiB
,GiB
, ...) are also supported.Unit Syntax Ampere amperes
,ampere
,A
Ångström angstrom
,Å
Astronomical unit AU
,au
,astronomicalunits
,astronomicalunit
Atmosphere atm
Bar bar
Barn barn
Becquerel becquerel
,Bq
Bel bel
Bit bits
,bit
Bits per second bps
British thermal unit BTU
Byte Bytes
,bytes
,Byte
,byte
,B
,Octets
,octets
,Octet
,octet
Calorie calories
,calorie
,cal
Candela candela
,cd
Coulomb coulomb
,C
Cup cups
,cup
DPI dpi
Day days
,day
,d
Degree degrees
,degree
,deg
,°
Dot dots
,dot
Electronvolt electronvolt
,eV
Euro euros
,euro
,EUR
,€
Farad farad
,F
Fluid ounce fluidounces
,fluidounce
,floz
Foot feet
,foot
,ft
Fortnight fortnights
,fortnight
Frame frames
,frame
Frames per second fps
Furlong furlongs
,furlong
Gallon gallons
,gallon
,gal
Gauss gauss
Gram grams
,gram
,grammes
,gramme
,g
Gray gray
,Gy
Hectare hectare
,ha
Henry henrys
,henries
,henry
,H
Hertz hertz
,Hz
Hogshead hogsheads
,hogshead
Hour hours
,hour
,h
Inch inches
,inch
,in
Joule joules
,joule
,J
Katal katal
,kat
Kelvin kelvin
,K
Lightyear lightyears
,lightyear
,ly
Liter liters
,liter
,litres
,litre
,L
,l
Lumen lumen
,lm
Lux lux
,lx
Meter meters
,meter
,metres
,metre
,m
Mile miles
,mile
Miles per hour mph
Millimeter of mercury mmHg
Minute minutes
,minute
,min
Mole mole
,mol
Month months
,month
Newton newton
,N
Ohm ohms
,ohm
,Ω
Ounce ounces
,ounce
,oz
PPI ppi
Parsec parsecs
,parsec
,pc
Partspermillion ppm
Partsperbillion ppb
Partspertrillion ppt
Partsperquadrillion ppq
Pascal pascal
,Pa
Percent percent
,pct
Person persons
,person
,people
Piece pieces
,piece
Pint pints
,pint
Pixel pixels
,pixel
,px
Poundforce pound_force
,lbf
Pound pounds
,pound
,lb
Psi psi
RPM RPM
,rpm
Radian radians
,radian
,rad
Rod rods
,rod
Second seconds
,second
,sec
,s
Siemens siemens
,S
Sievert sievert
,Sv
Tablespoon tablespoons
,tablespoon
,tbsp
Teaspoon teaspoons
,teaspoon
,tsp
Tesla tesla
,T
Thou thou
Tonne tonnes
,tonne
,tons
,ton
,t
US Dollar dollars
,dollar
,USD
,$
Volt volts
,volt
,V
Watthour Wh
Watt watts
,watt
,W
Weber weber
,Wb
Week weeks
,week
Yard yards
,yard
,yd
Year years
,year
Pros and cons
Reasons to use Insect
 Insect is open source.
 There is a web version that requires no installation.
 With both browser and terminal versions available, insect is truly crossplatform.
 Insect has firstclass support for physical units, including metric and binary prefixes. While evaluating your calculation, Insect ensures that you did not accidentally make any mistakes in combining the physical quantities.
 Insect supports an interactive style with its readlinebased interface. There is a saved history that can be browsed by pressing up and down keys. The history is also searchable via CtrlR.
 The syntax of Insect is rather strict. The parser does not try to be "smart" on syntactically incorrect input, so there shouldn't be any surprises  and you can trust the result of your calculation. The parsed user input is always prettyprinted for a quick doublecheck.
 Insect is written in PureScript and therefore benefits from all the safetyguarantees that a strictlytyped functional programming language gives you.
 The source code of purescriptquantities (the underlying library for physical units) as well as the code of Insect itself is extensively tested.
Reasons to choose an alternative
 Insect is a scientific calculator. It's not a computer algebra system that solves differential equations or computes integrals. Try WolframAlpha instead.
 There is no graphical user interface with buttons for each action (x², 1/x, DEG/RAD, etc.). Qalculate! is a fantastic tool that supports both text as well as graphical input.
 Insect supports a huge range of physical units: all SI units, all units that are accepted by SI as well as most units of the imperial and US customary systems (and many more). However, if you need something even more comprehensive, try GNU units.
 Insect is not a generalpurpose programming language. You could try Frink.
 Insect does not have a special mode for hexadecimal or binary numbers (yet).
FAQ

Why are Celsius and Fahrenheit not supported?
Compared to the SI unit Kelvin and in contrast to all other units, Celsius and Fahrenheit require an additive offset when converting into and from other temperature units. This additive offset leads to all kinds of ambiguities when performing calculations in these units. Adding two temperatures in Celsius, for example, is only meaningful if one of them is seen as an offset value (rather than an absolute temperature). Insect is primarily a scientific calculator (as opposed to a unit conversion tool) and therefore focuses on getting physical calculations right.
Even though °C and °F are not supported as builtin units, there are helper functions to convert to and from Celsius (and Fahrenheit):

fromCelsius
takes a scalar value that represents a temperature in Celsius and returns a corresponding temperature in Kelvin:> fromCelsius(0) = 273.15 K > k_B * fromCelsius(23) to meV = 25.5202 meV

toCelsius
takes a temperature in Kelvin and returns a scalar value that represents the corresponding temperature in Celsius:> toCelsius(70 K) = 203.15 > toCelsius(25 meV / k_B) = 16.963


Why is
1/2 x
parsed as1/(2x)
?Implicit multiplication (without an explicit multiplication sign) has a higher precedence than division (see operator precedence rules). This is by design, in order to parse inputs like
50 cm / 2 m
as(50 cm) / (2 m)
. If you meant ½ · x, write1/2 * x
. 
What is the internal numerical precision?
By default, Insect shows 6 significant digits in the result of the calculation. However, the internal numerical precision is much higher (30 digits).

How does the conversion operator work?
The conversion operator
>
attempts to convert the physical quantity on its left hand side to the unit of the expression on its right hand side. This means that you can write an arbitrary expression on the right hand side (but only the unit part will be extracted). For example:# simple unit conversion: > 120 km/h > mph = 74.5645 mi/h # expression on the right hand side: > 120 m^3 > km * m^2 = 0.12 m²·km # convert x1 to the same unit as x2: > x1 = 50 km / h > x2 = 3 m/s > x1 x2 = 10.8 km/h

What is the relation between the units
RPM
,rad/s
,deg/s
andHz
?The unit
RPM
(revolutions per minute) is defined via1 RPM = 1 / minute
where the1
on the right hand side symbolizes "1 revolution".As the base unit is the same (
1 / second
),RPM
can be converted torad / s
,deg / s
orHz
. Note, however, that1 RPM
does not equal2π rad / min
or360° / min
or1 Hz
, as some might expect. If you interested in computing the traversed angle of something that rotates with a given number of revolutions per minute, you need to multiply by2π rad
or360 °
because:1 RPM · (360°/revolution) = (1 revolution / minute) · (360° / revolution) = 360° / minute
Terminal version
In addition to the web interface, there is also a command line version which can by installed via npm:
npm install g insect
Note that this might fail if you run it with sudo
. Instead, set up a prefix directory and call npm install
as a user.
If you prefer not to install nodejs and npm, you can use one of the standalone binaries on the release page.
For Arch Linux, there is a package on AUR:
yaourt S insect
On Fedora 28+, you can install insect
from the official sources:
sudo dnf install insect
For Fedora versions 26 and 27, you need to enable this copr repository:
sudo dnf copr enable fnux/insect
For macOS, there is a Homebrew package:
brew install insect
Development
Insect is written in PureScript (see Getting Started guide). You can install all dependencies and build the whole project by running:
npm install
npm start
Open web/index.html in your browser.
Insect comes with a comprehensive set of unit tests. You can run them by calling
npm test