Evaluate
The /evaluate endpoint safely evaluates a mathematical expression and returns its result. It uses a Pratt parser — no eval() is ever called.
GET/v6/evaluate
How it works?
Expressions are tokenized then parsed recursively using binding powers (Pratt parsing). The result is computed directly from the AST — no eval(), no Function(). Two constants are available: pi (≈ 3.14159…) and e (≈ 2.71828…). Recursion depth is capped at 100 and expression length at 500 characters.
Parameters
| Parameter | Required | Description |
|---|---|---|
expr | Yes | The mathematical expression to evaluate (max 500 characters) |
precision | No | Number of decimal places in the result (0–15) |
Supported Operators
| Operator | Description |
|---|---|
+ | Addition |
- | Subtraction / unary negation |
* | Multiplication |
/ | Division |
% | Modulo |
^ | Exponentiation |
Unary - binds looser than ^, matching standard math convention: -2^2 evaluates to -4 (i.e. -(2^2)), not 4.
Available Functions
sin, cos, tan, asin, acos, atan, sqrt, abs, floor, ceil, round, log, log2, log10
Response Fields
| Field | Type | Description |
|---|---|---|
expr | string | The original expression |
result | number | The evaluated result |
Code Examples
curl -X GET \
"https://api.sylvain.sh/v6/evaluate?expr=2*%283%2B4%29%5E2&precision=2"Try It
Error Handling
If parameters are missing or invalid, the API will return an error:
| Error Message | Description |
|---|---|
Please provide a math expression (?expr={expression}) | The expr parameter is missing |
Expression is too long (max 500 characters) | The expression exceeds 500 characters |
Maximum expression depth exceeded | Nesting depth exceeds 100 levels |
Division by zero | The expression attempts to divide by zero |
Unknown identifier: {name} | An unknown constant or function name was used |
Invalid number: {num} | A number literal has more than one decimal point (e.g. 1.2.3) |
precision must be between 0 and 15 | The precision value is out of range |