Math question

Using Arduino Programming Questions
#1

I apologize, but my google-fu is apparently non-existent tonight. And I keep finding conflicting info on order of operations with Arduino.

Can someone explain to me why this:

float percent = ( (transitionTime * 60) - ( ( sunriseTime + (transitionTime * 60) ) - now.unixtime() ) ) / (transitionTime * 60 );

Does not return the same as this:

float percent = (transitionTime * 60) - ( ( sunriseTime + (transitionTime * 60) ) - now.unixtime() );
percent = percent / ( transitionTime * 60 );

Thanks!

#2

In the first code, all the values are integers, so integer arithmetic is performed.

In the second code, integer arithmetic is performed, and the result stored in a float. Then, floating point arithmetic is performed.

#3

It might be because you need to force it to do floating point math

try this?

... / ( (float) transitionTime * 60 );

or maybe even this

... / ( transitionTime * 60.0 );

#4

Thanks guys. You are right on. I did Ps991 and added the 60.0 on the end.

#5