I have some code that generates random numbers on the Arduino, it then sends these random numbers firstly, using Serial.print(float data,int lenght) and as a floating point number using the following function
void send_float (float arg)
{
// get access to the float as a byte-array:
byte * data = (byte *) &arg;
// write the data to the serial
Serial.write (data, sizeof (arg));
Serial.println();
}
I then receive this data using python, take the absolute difference of the two values, discard any differences less than the length with which I send the string and output the rest to the screen.
I observe two things, a) Fluctuations of the order with which I send the data (ie. if I send to 6 decimal places then I see fluctuations of ~1e-6), this is reasonable and b) I see fluctuations of absolute value 1e-8 or lower independent of what accuracy I send the string.
Even if I send the string to 11 decimal places, when I compare against the float I see fluctuations up to but not above 1e-8.
Why? This doesn't make any sense. My full code is actually the answer to an old unanswered stack exchange question unanswered stack exchange question
I have some code that generates random numbers on the Arduino, it then sends these random numbers firstly, using Serial.print(float data,int lenght) and as a floating point number using the following function
void send_float (float arg)
{
// get access to the float as a byte-array:
byte * data = (byte *) &arg;
// write the data to the serial
Serial.write (data, sizeof (arg));
Serial.println();
}
I then receive this data using python, take the absolute difference of the two values, discard any differences less than the length with which I send the string and output the rest to the screen.
I observe two things, a) Fluctuations of the order with which I send the data (ie. if I send to 6 decimal places then I see fluctuations of ~1e-6), this is reasonable and b) I see fluctuations of absolute value 1e-8 or lower independent of what accuracy I send the string.
Even if I send the string to 11 decimal places, when I compare against the float I see fluctuations up to but not above 1e-8.
Why? This doesn't make any sense. My full code is actually the answer to an old unanswered stack exchange question
I have some code that generates random numbers on the Arduino, it then sends these random numbers firstly, using Serial.print(float data,int lenght) and as a floating point number using the following function
void send_float (float arg)
{
// get access to the float as a byte-array:
byte * data = (byte *) &arg;
// write the data to the serial
Serial.write (data, sizeof (arg));
Serial.println();
}
I then receive this data using python, take the absolute difference of the two values, discard any differences less than the length with which I send the string and output the rest to the screen.
I observe two things, a) Fluctuations of the order with which I send the data (ie. if I send to 6 decimal places then I see fluctuations of ~1e-6), this is reasonable and b) I see fluctuations of absolute value 1e-8 or lower independent of what accuracy I send the string.
Even if I send the string to 11 decimal places, when I compare against the float I see fluctuations up to but not above 1e-8.
Why? This doesn't make any sense. My full code is actually the answer to an old unanswered stack exchange question
Serial, Numbers sent as Floating Point and Characters are different at 1e-8 level
I have some code that generates random numbers on the Arduino, it then sends these random numbers firstly, using Serial.print(float data,int lenght) and as a floating point number using the following function
void send_float (float arg)
{
// get access to the float as a byte-array:
byte * data = (byte *) &arg;
// write the data to the serial
Serial.write (data, sizeof (arg));
Serial.println();
}
I then receive this data using python, take the absolute difference of the two values, discard any differences less than the length with which I send the string and output the rest to the screen.
I observe two things, a) Fluctuations of the order with which I send the data (ie. if I send to 6 decimal places then I see fluctuations of ~1e-6), this is reasonable and b) I see fluctuations of absolute value 1e-8 or lower independent of what accuracy I send the string.
Even if I send the string to 11 decimal places, when I compare against the float I see fluctuations up to but not above 1e-8.
Why? This doesn't make any sense. My full code is actually the answer to an old unanswered stack exchange question