double gets automatically rounded, not enough precision...

Projects Programming
1

I have the following function which I need to convert some coordinates:

double convertRawToDecimal(double latOrLong){
  int decimalDegrees = (int) latOrLong / 100;
  Serial.println(decimalDegrees);
  double minutes = latOrLong - decimalDegrees * 100;
  Serial.println(minutes);
  double temp = minutes/60.0;
  Serial.println(temp);
  double result = decimalDegrees +temp;
  return result;
}

The important part is happening where I divide minutes by 60.
I call the method with for example 4730.59 and when I print out the temp variable which should hold something like 0.5098333 it prints out 0.51 . Now I am wondering is the println method pulling my leg or is the value stored in temp really 0.51

Thanks for helping out

2

multiply the number by 1000 and see how many significant digits you get.

3

Try:

Serial.println(minutes,4);

Note also that double & float are the same size in an arduino context; you're not getting any additional precision by specifying double.

4

When in doubt

5

When you calculate using your double it won´t round, all decimals are used for calculation.

6

TempleClause:
Now I am wondering is the println method pulling my leg

See Reply #3. The println() method is doing what it is supposed to, it is just not what you expected.

7

I'd like to also add that unless you have a due, there is also no difference between float and double, both have the same precision.