multiMap outputing more significant figures

Projects Programming
1

I feel as though I'm missing something obvious here but I'm trying to use multiMap to interpolate data and it's only outputting 2 significant figures for the results.

When I use the regular map function it will output 4 significant figures which is what I'm after.

   float calibration[] = { 0, 2, 5, 10, 14, 15 };
   float sensorValue[] = { 0, 65, 213, 534, 759, 802 };
   float distance;
   float input;



void setup() {
  Serial.begin(9600);
  
}

void loop() {
  
     input = analogRead(A0);
    //float distance = map(input,0,802,0,1500) / 100.; //Calibrate here. map(zero value during calibration, high number during calibration, 0, 1500)
    float distance = FmultiMap(input, sensorValue, calibration, 6);
    
    Serial.println(distance);
    delay(10);

}


//****float multiMap
float FmultiMap(float input, float* sensorValue, float* calibration, uint8_t size)
{
  // take care the value is within range
  // input = constrain(input, sensorValue[0], sensorValue[size-1]);
  if (input <= sensorValue[0]) return calibration[0];
  if (input >= sensorValue[size-1]) return calibration[size-1];

  // search right interval
  uint8_t pos = 1;  // sensorValue[0] already tested
  while(input > sensorValue[pos]) pos++;

  // this will handle all exact "points" in the _in array
  if (input == sensorValue[pos]) return calibration[pos];

  // interpolate in the right segment for the rest
  return map(input, sensorValue[pos-1], sensorValue[pos], calibration[pos-1], calibration[pos]);
}
2

Try:

Serial.println(distance, 4);
3

Thanks for the reply. That gives me additional decimal places on the print out but they are just 0's.

I'm looking for the output readouts in between the calibration[] numbers for the corresponding sensor value

4

I caught a mistake in my initial code for the last line of the FmultiMap read that I corrected for interpolting the data but it didn't help my problem of only display the numbers listed in the calibration array.

   return (input-sensorValue[pos-1])*(calibration[pos]-calibration[pos])/(sensorValue[pos]-sensorValue[pos-1])+calibration[pos-1];
5

Annnnd that's where the problem was again. forgot a -1. Fixed everything and problem solved.

   return (input-sensorValue[pos-1])*(calibration[pos]-calibration[pos-1])/(sensorValue[pos]-sensorValue[pos-1])+calibration[pos-1];