isnan()

[Math]

bool isnan(double x);

Description

Returns true if x is NaN, false otherwise.

Parameters

x: The value to check if it is NaN.

Returns

true if x is NaN, false otherwise.

Example Code

The code reads the value of two potentiometers connected to pins INX and INY and place true on pin OUT if the $\frac{x}{y}$ is NaN, false otherwise.

void setup() {
    pinLabel(0, "INY");  // set the label of pin 0 to "INY"
    pinLabel(1, "INX");  // set the label of pin 1 to "INX"
    pinLabel(2, "OUT");  // set the label of pin 2 to "OUT"
    pinMode(2, OUTPUT);  // set pin 2 as output
    pinLabel(3, "OUT2"); // set the label of pin 3 to "OUT2"
    pinMode(3, OUTPUT);  // set pin 3 as output
    
    pinLabel(4, "VCC");  // set the label of pin 3 to "VCC"
    powerPin(4);         // set pin 4 as power pin
    pinLabel(5, "GND");  // set the label of pin 4 to "GND"
    groundPin(5);        // set pin 5 as ground pin
}

void loop() {   
    int val_x = analogRead(0);  // read the value of the potentiometers
    int val_y = analogRead(1);
    // map the value of the potentiometers from 0 to 1023
    // to the range of 0 to 10
    double x = map(val_x, 0, 1023, 0, 10);
    double y = map(val_y, 0, 1023, 0, 10);   
    bool z = isnan(x / y); // check if x/y is NaN   
    digitalWrite(2, z); // write the value of z to pin 2
}