Problem doing math with very small numbers in Arduino IDE

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1 
  int m = 0.0;
  float vout = 0.0;
  float rT = 0.0;
  float tempC = 0.0;
  float up = 0.0;
  float e = 0.0;
  float inside = 0.000;
  m = analogRead(A9);
  Serial.print("M = ");
  Serial.println(m);
  vout = m*(0.0048828125);
  Serial.print("Vout = ");
  Serial.println(vout);
  rT = (50000/vout)-10000;
  Serial.print("rT = ");
  Serial.println(rT, 10);
  e = exp(1);
  up = -3380/25;
  Serial.print("up = ");
  Serial.println(up);
  inside = 10000*(pow(e, up));
  Serial.print("inside the parenthesis = ");
  Serial.println(inside,60);
  tempC = (rT/(inside));
  tempC = tempC*(pow(10,55));
  Serial.println(tempC);
  tempC = log(tempC);
  tempC = 3380/tempC;
  Serial.print("tempC = ");

I attached an image file of the equation I am trying to do. This equation gives temperature in Celsius based on resistance (rT) which I have already calculated to be around 9200. The issues start when I first try to print tempC and it tells me that it is "inf" when in reality it is just a very large number. Any help would be appreciated.

2020-10-18.png
2020-10-18.png1793×1065 39.7 KB

2020-10-18.png
2020-10-18.png1793×1065 39.7 KB

2 
tempC = tempC*(pow(10,55));

IIRC, floats are good up to about 1038

The code you posted doesn't compile, BTW

3

Seems you're working with a 10k thermistor.

0.0048828125
When will that happen, with a noisy/unstable 5volt supply and a 10-bit A/D.

The default A/D of an Arduino is ratiometric.
A resistor/thermistor returns a ratio of the range of the A/D.
Voltage is (should be) irrelevant.

Google "Steinhart-Hart equation".
Or study one of the many thermistor sketches.
They first calculate the resistance of the thermistor, and from there temperature.
Leo..

4

There is little point in doing an integer divide here.

  up = -3380/25;

About 54 of the 60 digits printed by this line are nonsense:

  Serial.println(inside,60);