Student Support Forum: 'Derivative of a real function gives Complex res...' topicStudent Support Forum > General > "Derivative of a real function gives Complex res..."

 Next Comment > Help | Reply To Topic
 Author Comment/Response Dimanche 11/22/12 8:24pm Hi there! I have found an interesting bug (or at least I can't explain this): f1[x_] := Sin[2*Pi*x/10] + I*Cos[2*Pi*x/20] f2[x_] := Abs[f1[x]] f3[x_] := f2'[x] f3[1] Output looks like: (-(1/40) I (-1 + Sqrt[5]) \[Pi] + 1/20 (1 + Sqrt[5]) \[Pi]) Derivative[1][Abs][ Sqrt[5/8 - Sqrt[5]/8] + I Sqrt[5/8 + Sqrt[5]/8]] So, initially I had a complex function (f1), then turned it into a real value function (f2), then attempted to get a derivative - voila! - imaginary unit is back! How?!!! Just in case - attached is a screenshot. Attachment: glitch.JPG, URL: ,

 Subject (listing for 'Derivative of a real function gives Complex res...') Author Date Posted Derivative of a real function gives Complex res... Dimanche 11/22/12 8:24pm Re: Derivative of a real function gives Complex... Nasser M. Ab... 11/24/12 00:50am Re: Derivative of a real function gives Complex... Sumit 11/24/12 02:03am Re: Re: Derivative of a real function gives Com... Dimanche 11/24/12 12:03pm
 Next Comment > Help | Reply To Topic