mpeqs

Exact answers for the arithmetic a language model should not be doing itself.

pip install mpeqs

import mpeqs

mpeqs.solve({"solver": "arith", "answer": "(17/100)*250"})   # Fraction(85, 2)

The model names a solver and fills its slots. This evaluates the spec exactly, or refuses by name — it never guesses, and it never returns a number it could not derive.

The refusal is the point. A solver that cannot evaluate a spec raises Refusal with a reason, and that reason is a routing signal: it tells the caller to ask the model, rather than quietly handing back a wrong number.

try:
    mpeqs.solve({"solver": "arith", "answer": "1/0"})
except mpeqs.Refusal as why:
    ...   # ask the model; the record declined this one

Shape disposes over name. A model that picks the wrong solver but fills the right slots has still described the problem correctly, so a spec carrying an answer key is arithmetic whatever it calls itself. Pass repair=False to turn that off.

What is exact and what is not

Results come back as fractions.Fraction, so nothing is lost on the way out. The exactness is in the arithmetic, not in the parsing: a ratio written as a ratio stays exact, while a decimal literal is read as a float first.

mpeqs.solve({"solver": "arith", "answer": "1/10+2/10"})   # Fraction(3, 10)  exact
mpeqs.solve({"solver": "arith", "answer": "0.1+0.2"})     # the binary expansion

Solvers

arith, geometry, iterate, modular, multisearch, polynomial, and the named families behind them — factorisation, gcd/lcm, linear systems, quadratics, remainders, combinatorics, rates, mixtures, ratios, base conversion.

mpeqs.solvers() lists what a given build dispatches to.

No dependencies

The whole library is standard library. One py3-none-any wheel serves Linux, macOS and Windows on every supported interpreter, the install is instant, and a test asserts that no third-party import creeps in.

Licence

The mpedb License 1.0 — free of charge for every person and every organization, except that a group over five billion dollars in revenue or valuation owes seven US cents per device, once. Not an OSI-approved licence.