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    <p>If this is a function that gets called often I would stay away from modular division because it is a relatively expensive operation. In your case, the turns can only ever exceed Pi or -Pi by less than one revolution so we can use adding or subtracting Pi from the value to correct for this mistake which is a cheaper option performance wise.</p> <pre><code>//helper function to determine the distance, in radians, between two headings float AngularDist(float heading1, float heading2) //assumes all headings are between -Pi and Pi { if(heading1*heading2&gt;0.0) //this checks if they have the same sign. If so result will be positive { return(abs(heading1-heading2)); } else //If the headings don't have the same sign we need to do some extra math to check whether it is shorter to turn clockwise or counterclockwise to reach other angle { float clockwise=abs(heading1)+abs(heading2); float counterclockwise=2.0*Pi-clockwise; if(clockwise&lt;counterclockwise) return(clockwise); else return(counterclockwise); } } float turnToRequestedHeading(float initialHeading, float requiredHeading, float turnRate) { if((AngularDist(initialHeading,requiredHeading)/turnRate&lt;1.0) //if the turn is too small return required { return(requiredHeading) } else { float positiveTurn=initialHeading+turnRate //need to check if variable is greater than Pi if(positiveTurn&gt;Pi) positiveTurn-=Pi; float negativeTurn=initialHeading-turnRate //need to check if we variable is less than -Pi if(negativeTurn&lt;-Pi) negativeTurn+=Pi; if(AngularDist(negativeTurn,requiredHeading)&lt;AngularDist(positiveTurn,requiredHeading)) return(negativeTurn); else return(positiveTurn); } } </code></pre> <p>EDIT Saw that my original code to check if the new heading was less than one turn rate away incorrectly used absolute value and corrected it. EDIT 2: commenter is right that the case for handling wrapping from a positive to negative number was incorrect. Fixed it by adding a helper function that just calculates distance. I imagine that this will be inlined by the compiler, but it might be worth checking the disassembly to make sure that it is.</p>
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    1. POStuck on some angular arithmetic
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    1. COCheers. I'll have to think about using your alternative to % as other parts of my code may produce > Pi values. I may have to check every time
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    2. CO@Samsdram I'm not sure that the above code is correct. When I plug values of -3, 2.5 and 0.5 in for `initialHeading`, `requiredHeading` and `turnRate` respectively, I think I should get back a value of 2.7831... however the above returns a value of 2.5.
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      1. USdave.c
    3. CO@dave.c Thanks for catching that error. Posted a fix.
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