math

Overview

The math node performs mathematical operations on numeric message values. Supports basic arithmetic, power and root functions, trigonometry, rounding, logarithms, and random number generation. Ideal for unit conversions, sensor calibration, and computed metrics.

Properties

Operations Reference

add:      value + operand
subtract: value - operand
multiply: value * operand
divide:   value / operand
pow:      value ^ operand

sqrt:   square root
abs:    absolute value
ceil:   round up
floor:  round down
round:  nearest integer

sin:    sine (radians)
cos:    cosine (radians)
tan:    tangent (radians)
log:    natural logarithm
exp:    e ^ value
random: 0.0 - 1.0

Example: Calculate Power Consumption

Compute wattage from voltage and current sensor readings (P = V * I).

// Math node configuration
{
  "operation": "multiply",
  "operand": 0,            // Use msg.operand dynamically
  "property": "payload.voltage",
  "precision": 2,
  "output": "payload.watts"
}

// Flow: batch (concat) → function → math
//
// Function node prepares:
msg.payload.voltage = msg.payload.voltage;  // e.g., 230
msg.operand = msg.payload.current;          // e.g., 4.5
return msg;

// Math node computes: 230 * 4.5 = 1035.00
//
// Output:
{
  "payload": {
    "voltage": 230,
    "current": 4.5,
    "watts": 1035.00
  }
}

Example: Convert Sensor Units

Convert temperature readings from Celsius to Fahrenheit using chained math operations.

// Step 1: Multiply node
{
  "operation": "multiply",
  "operand": 1.8,
  "property": "payload",
  "precision": 2
}

// Step 2: Add node
{
  "operation": "add",
  "operand": 32,
  "property": "payload",
  "precision": 1
}

// Flow: sensor (25.0 C) → multiply (45.0) → add (77.0 F)
//
// Formula: F = (C * 1.8) + 32
// Input:  25.0
// After multiply: 25.0 * 1.8 = 45.0
// After add:      45.0 + 32  = 77.0

// Also useful for:
// - hPa to inHg:  multiply by 0.02953
// - meters to feet: multiply by 3.28084
// - ADC to voltage: multiply by (Vref / 1023)

Example: ADC Sensor Calibration

Scale raw ADC readings to real-world units with offset correction.

// Step 1: Subtract zero-offset
{
  "operation": "subtract",
  "operand": 102,         // Sensor reads 102 at zero
  "property": "payload"
}

// Step 2: Scale to real units
{
  "operation": "multiply",
  "operand": 0.0489,      // Scale factor for 0-50 PSI
  "property": "payload",
  "precision": 1
}

// Raw ADC: 614 → subtract → 512 → multiply → 25.0 PSI

Common Use Cases