calc.nvim

Work in progress. Interactive symbolic RPN calculator for Neovim powered by SymPy.

Features

• RPN stack-based symbolic mathematics
• LaTeX input and output via latex2sympy2
• Environment variables for storing and recalling expressions
• Stack operations: dup, drop, swap, pick, undo
• Calculus: differentiation, determinant
• Rich display with virtual text, extmarks, and LaTeX conceal
• Undo history for the stack

Requirements

• Neovim 0.9+
• Python 3 with pynvim, sympy
• latex2sympy2 (optional, for LaTeX push)

Installation

lazy.nvim

{
  "splyashka/calc.nvim",
  build = ":UpdateRemotePlugins",
  init = function()
    vim.g.python3_host_prog = vim.fn.expand("~/.virtualenvs/neovim/bin") .. "/python3"
  end,
  keys = {
    { "<leader>cl", ":CalcPushLatexVisual<CR>", desc = "Push LaTeX selection", mode = "x" },
  },
}

Run :Calc to open the calculator window.

Note: Make sure your Python 3 host (set via g:python3_host_prog) has pynvim and sympy installed. latex2sympy2 is optional (needed for LaTeX push). Run :checkhealth after installation to verify.

Usage

Commands

:Calc <op> — execute an operation on the RPN stack.

Command	Effect
+, -, *, /	Pop top 2, push result
dup	Duplicate top of stack
drop	Remove top of stack
swap	Swap top 2 elements
pick N	Push copy of Nth element (0-indexed from top)
undo	Restore previous stack state
!	Store: pop a Symbol (name), pop next value, save to env
@	Substitute: pop a Symbol, pop an expression, substitute from env
eval	Substitute all env variables into the top expression
diff sym1 ...	Differentiate top expression wrt given symbols
det	Determinant of top expression (must be a matrix)
(any other value)	Push it as a SymPy expression

Buffer keymaps (normal mode)

Key	Action
+, -, *, /	Add, subtract, multiply, divide
<CR>	Duplicate top
.	Repeat last command
dd / <BS>	Drop top
!	Store in env
yl	Copy LaTeX of expression under cursor
I	Open floating LaTeX input window
s	Swap top 2
u	Undo
0 – 9	Push digit
i	Enter :Calc command
ad	Enter :Calc diff (differentiate)
vD	Compute determinant

Visual mode

Key	Action
<leader>cl	Push visual selection as LaTeX

Examples

Differentiate — type :Calc diff x, or press ad and type x:

x^2 + 3*x  →  2*x + 3

Matrix determinant — push a sympy matrix, press vD:

Matrix([[1, 2], [3, 4]])  →  -2

Store and recall — push a value, then push a symbol on top and press !:

42       — push value
ans      — push symbol
!        — store (pops symbol then value) → env["ans"] = 42

ans + 1  — push expression
ans      — push symbol
@        — subst (pops symbol then expression) → 43

LaTeX input — press I, type LaTeX in the float buffer, press <CR> to commit:

\frac{d}{dx} x^2  →  2*x

Roadmap

• Healthcheck (:checkhealth) for sympy / latex2sympy2
• K hover for info about the expression under cursor
• Configurable keymaps

License

MIT