Exact calculator
Evaluate an arithmetic expression exactly, with no floating-point error, and return the result as a decimal string.
Details
Supports: + - * / ^, parentheses, 7% (= 0.07), variables, and sqrt, cbrt, root, abs, floor, ceil, round, round_even, round_to, trunc, min, max, sum, avg, mod, ln, log10, log2, log, exp, pow, percent, pi, e.
Exact: + - * / and integer powers are exact fractions (0.1 + 0.2 = 0.3). sqrt, ln, exp and non-integer powers are computed to 50+ digits and marked exact: false.
Rounding: decimals, significant digits, or round_to a step such as 0.05 (Swiss cash rounding), with 7 rounding modes.
Price: CHF 0.001 per call (first 100 calls per day free).
Example: {"expression":"0.1 + 0.2"} → {"value":"0.3","exact":true}.
Call it
RESTcurl -X POST https://api.tausendwerk.xyz/v1/calculate \
-H "Content-Type: application/json" \
-d '{"expression":"0.1 + 0.2"}'calculateAfter the free 100 calls per day, add a key: Authorization: Bearer tw_live_…. Pricing
Try it
Runs against the live API with the free allowance.
Input schema JSON Schema
{
"type": "object",
"additionalProperties": false,
"required": [
"expression"
],
"properties": {
"expression": {
"type": "string",
"minLength": 1,
"maxLength": 5000
},
"variables": {
"type": "object",
"additionalProperties": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"description": "Named values, e.g. {\"price\": \"19.90\", \"qty\": 3}"
},
"decimals": {
"type": "integer",
"minimum": 0,
"maximum": 100,
"description": "Round the result to this many decimal places."
},
"significant": {
"type": "integer",
"minimum": 1,
"maximum": 60,
"default": 30,
"description": "Significant digits for non-terminating results. Default 30."
},
"round_to": {
"type": "string",
"pattern": "^\\d*\\.?\\d+$",
"description": "Round to a multiple of this step, e.g. \"0.05\" for Swiss cash rounding."
},
"rounding": {
"type": "string",
"enum": [
"half_up",
"half_even",
"half_down",
"up",
"down",
"toward_zero",
"away_from_zero"
],
"description": "Rounding mode for decimals and round_to. Default half_up."
}
},
"examples": [
{
"expression": "0.1 + 0.2"
},
{
"expression": "price * qty * (1 + vat)",
"variables": {
"price": "19.90",
"qty": 3,
"vat": "0.081"
},
"round_to": "0.05"
}
]
}