, N of N-point-fft is chosen? What can go wrong if I don't select it to be  power of 2? How is this N related to sampling frequency?

A:

Firstly, you need to know that the FFT computes the DFT (discrete Fourier transform) in an efficient manner. Hence, the output of an N-point FFT and N-point DFT are exactly the same. 
Now, especially, if N is a power-of-two, the FFT can be calculated very efficiently. Though, if N can be factorized into rel. small prime numbers (2, 3, 5), still the calculation can be done very efficiently. Strictly speaking, the Radix-2 FFT only works, if N is power-of-two. However, in common implementations in software, N can be any number and the implementation chooses the appropriate algorithms for most efficient calculation.
Hence, if N is power of two, the calculation by FFT is just a bit faster, compared to when N would be a large prime number. 
Regarding sampling frequency: If $F_s$ is your sampling frequency and $T$ is the duration of the FFT window, then $N=TF_s$. It's hard to answer more detailed what you mean by relation to sampling frequency, because I dont know exactly what you are asking.
Regarding your comment: The DFT maps a subset of the frequency range $[0,\dots,F_s]$  to the $N$ DFT-bins, which are indexed by $k=0,\ldots,N-1$. Since all frequency bins in the DFT output have the same distance to each other (i.e. they are linearly spaced), you immediately end up with $f=\frac{k}{N}F_s$, i.e. the $k$th bin corresponds to the physical frequency $f=\frac{k}{N}F_s$.  

 Q:

Intent message passing confusion

I am a little confused with intent and message passing in android.Basically my current predicament:
A screen is shown to user displaying list of animals, when a user clicks a row, e.g. a Tiger, information about this animal will be displayed on the next screen/activity.
I have the framework for the application largely taken care of, so when a user selects from animal list they are brought to the Animal activity/class, but
, N of N - point - fft is chosen? What can go wrong if I don't choose it to be   exponent of 2? How is this N related to sampling frequency? 

 deoxyadenosine monophosphate: 

 first, you need to know that the FFT computes the DFT (discrete Fourier transform) in an effective manner. therefore, the output of an N - point FFT and N - point DFT are exactly the same. 
 immediately, especially, if N is a power - of - two, the FFT can be count very efficiently. Though, if N can be factorize into rel. small prime number (2, 3, 5), still the calculation can be done very efficiently. rigorously speaking, the Radix-2 FFT only works, if N is office - of - two. However, in common implementations in software, N can be any act and the implementation choose the appropriate algorithms for most efficient calculation. 
 Hence, if N is power of two, the calculation by FFT is barely a bit faster, compared to when N would be a large prime number. 
 Regarding sampling frequency: If $ F_s$ is your sampling frequency and $ T$ is the duration of the FFT window, then $ N = TF_s$. It's hard to answer more detailed what you mean by relation to sampling frequency, because I do nt know exactly what you are ask. 
 Regarding your comment: The DFT map a subset of the frequency stove $ [ 0,\dots, F_s]$   to the $ N$ DFT - bins, which are indexed by $ k=0,\ldots, N-1$. Since all frequency bank identification number in the DFT output have the same distance to each other (i.e. they are linearly space), you immediately end up with $ f=\frac{k}{N}F_s$, i.e. the $ k$th bin corresponds to the physical frequency $ f=\frac{k}{N}F_s$.  

  Q: 

 Intent message passing confusion 

 I am a little confused with intent and message passing in android. Basically my current predicament: 
 A screen is shown to user displaying list of animal, when a user snap a rowing, e.g. a Tiger, information about this animal will be displayed on the next sieve / activity. 
 I have the framework for the lotion largely taken concern of, so when a user selects from animal tilt they are brought to the Animal activity / class, but
, N lf N-point-fft is chosen? Wmat can go wrong if I dmn't semect it go be  power of 2? How is this N relauvd to sampling frequevcy?

A:

Firstpy, you nwed uo know that the HRT compmces tgc DFT (viscrete Fouriet transform) hn an efficiend oauner. Hence, the output of an N-point FST and M-plint DFT are evactkr ths same. 
Now, especially, if N is a poser-of-twm, the FFT can be calculated very efficifntlj. Though, if N can he factorizgs igro rel. small prime numbers (2, 3, 5), stilm the calculation can be done vdry eyficiently. Wteichny speaking, the Gadix-2 FFT onln works, if N ix power-of-two. Hpweter, un common implementatmons in software, N cwn be any nbmber and the implemebtqtion chomses rhe apkro'rizte alhormthms for mkst efficiebt calculation.
Hence, is N is power or two, ehq calculation by FFT is just a bit fasttr, cojpared to when N would ve a large prime numbgr. 
Regardigg sampling frequency: If $F_s$ is your sampling freqgency xnd $T$ kw hhe duration of the FFT window, then $N=TF_s$. It's rzrc no answer more debailed what you mesn bu relation to rampliuf rrequency, because L dont hnow wxactly wrat uou are asking.
Regarding youe comment: Thv DFR maps a subset of the frequeucy ramge $[0,\dpts,F_s]$  to the $N$ DFT-bins, whidh are indeded by $k=0,\lsuts,N-1$. Since all ffeqlencf bins in the DFT output hwve the seme dnstance go esch otrer (i.e. thej are linearly spaced), yok immgdiateny end up aith $f=\frac{k}{N}F_s$, i.e. the $k$th bin corresponds to jhe phjsical frzquencn $f=\frac{k}{N}F_s$.  

 Q:

Yntent message passiny confjsion

I am z littlx confused wyth intent ang message pasving in wndriid.Bqsicallh my current prrdicament:
C scrwen is shown to uscr dirllaying list of anumals, when a usrr zliskd e row, a.g. a Tiger, itforoatkpn abuut this anlmau wikl be displayed on tve nsxt screen/activity.
O mave the drameworh for the appkication largely twken rare oh, so wnen a user selects from animal liat they age nrought to thq Anlmal activity/ckass, but
, N of N-point-fft is chosen? What wrong I don't it to be this related to sampling A: Firstly, you to know that the FFT computes DFT (discrete Fourier transform) in an efficient manner. Hence, the output of an FFT and N-point DFT are exactly the same. Now, especially, if N is power-of-two, FFT be very efficiently. Though, if N can be factorized into rel. small prime numbers (2, 3, 5), the calculation can be done very efficiently. Strictly the Radix-2 FFT only if N is power-of-two. However, common in software, can any and the implementation the appropriate algorithms for most efficient calculation. Hence, if N is power of two, the calculation by is just faster, compared when would a large prime sampling frequency: If $F_s$ is your $T$ is the duration of the FFT window, $N=TF_s$. It's to answer more detailed what you by relation to sampling frequency, because I dont exactly what you are asking. Regarding your comment: The DFT maps a subset of the $[0,\dots,F_s]$ to the $N$ which are indexed $k=0,\ldots,N-1$. all bins the DFT have the same distance to each other (i.e. they are linearly you immediately end up with $f=\frac{k}{N}F_s$, i.e. the $k$th bin the frequency $f=\frac{k}{N}F_s$. Q: message passing confusion I a confused with intent and in my screen shown user displaying list of when a user clicks a e.g. a Tiger, information displayed on the next screen/activity. I have the for the application largely taken care of, when a user selects from animal list they are brought to the activity/class, but
, N of N-point-fft is chosen? What cAn go wrong iF I don'T seLecT iT to bE  powEr of 2? How is this N RElatEd to sampling frequency?

A:

firstLy, YOu neED tO know That the ffT COMpuTeS tHe DfT (DIsCrete fouRier traNsform) in an EffIcIent manner. HeNCe, The output oF an n-point FFT and n-poInt DFT ArE exACtly tHe sAme. 
NoW, especIAlly, if n is a power-Of-TWo, the Fft can be cALCuLateD very efficiently. THOuGH, if N can be factoRized iNtO ReL. SMalL prIme numbers (2, 3, 5), StIll thE CalculaTIoN CAN be DOne very efficiEntly. StrictLY spEaking, ThE RaDIx-2 FFT oNly woRkS, If N Is power-of-twO. HowEver, in comMon impLEmentatIOns in soFtware, n caN be Any nUMbEr And ThE ImpLEmEntATioN chooses ThE aPpropRiatE ALGOritHms For mOst efFicient calculAtiOn.
HeNCe, iF N is pOwer oF two, ThE calcUlatioN by FFt iS just a bit faster, CompAred to wheN N wOuLd bE a Large PRime nuMbeR. 
ReGarding SamplinG FreQuENCY: IF $F_s$ is your sampling fReQUEnCy and $T$ is The durATiOn OF the FFT wInDow, Then $n=tf_s$. It's Hard TO aNswer morE detaiLEd WhAt you meAn By relaTiOn tO saMplinG FreqUency, bEcause I dOnt knOW exactly what yoU Are asking.
RegaRDiNG YoUR comMenT: The DFT maps A subSEt of The fREqUenCY rangE $[0,\dots,f_s]$  TO tHE $N$ DFT-bins, which are inDeXed by $k=0,\Ldots,n-1$. Since all freqUency bins iN THE DFT outpUt haVE tHE same distance tO each Other (i.e. theY Are lineaRly spAced), you iMmediatelY ENd up with $F=\frAc{k}{n}F_s$, I.e. tHE $K$tH bin corresponDS To thE pHysical FreQuency $f=\FraC{k}{N}f_s$.  

 Q:

intEnT message pAssing coNfUsIoN

I Am a LittlE Confused WiTh iNtEnt And meSSage paSsing In anDrOiD.basIcally mY CuRREnt pReDiCameNt:
A ScReen iS shoWN to User disPlaying liSt oF AnimAlS, wHen a useR clicks a row, e.g. A TIger, informAtIon About tHIS animal wIll be displayed on the next SCreen/acTivIty.
I hAve tHe framewoRk fOr the aPplICation LargelY takeN cAre OF, So wheN A UsEr sElEcts from anIMAl lIst thEy Are bRought tO the Animal activity/CLasS, but
, N of N-point-fft is chos en? What c an go  wr ong  i f Idon' t select it to be power of 2? How is thi s N r el a tedt osampl ing fre q ue n c y?
A :
Fi rs t ly , you  ne ed to k now that t heFF T computes t h eDFT (discr ete  Fourier tra nsf orm) i nane ffici ent  mann er. He n ce, th e outputof an N-p o int FFT a nd  N-p oint DFT are exac t ly the same. 
Now , espe ci a ll y ,  if  Nis a power -o f-two ,  the FF T  c a n bec alculated ver y efficient l y.Though ,ifN  can b e fac to r ize d into rel.  sma ll primenumber s  (2, 3, 5), sti ll the  ca lcu lati o nca n b ed one ve rye ffi ciently.  S tr ictly  spe a k i n g, t heRadi x-2 F FT only works , i f Ni s p ower- of-tw o. H ow ever,  in co mmonim plementations i n so ftware, N  ca nbean y num b er and  th e i mplemen tationc hoo se s t he  appropriate algor it h m sfor most  effic i en tc alculati on .
H ence , if Nis p o we r of two , thec al cu lationby  FFT i sjus t a  bitf aste r, com pared to  when N would be a l a rge prime num b er . 
R e gard ing  sampling f requ e ncy:  If$ F_ s$i s you r sam pl i ng frequency and $T$ i sthe du ratio n of the FFTwindow, th e n $N=TF_s$ . It ' sh ard to answermoredetailed w h at you m ean b y relati on to sam p l ing freq uen cy,  be cau s e  I  dont know ex a c tlywh at youare  asking .
R ega rdi ngyo ur commen t: The D FT  m ap sa s ubset of the f re que nc y r ange$ [0,\do ts,F_ s]$ t ot he$N$ DFT - bi n s , wh ic hareind ex ed by  $k= 0 ,\l dots,N- 1$. Since  al l  fre qu en cy bins  in the DFT o ut put have t he  sa me dis t a nce to e ach other (i.e. they ar e  linear lyspace d),you immed iat ely en d u p  with$f=\fr ac{k} {N }F_ s $ , i.e . th e $ k$ th bin cor r e spo nds t othephysica l frequency $f=\fr a c{k }{N}F_s$.  
 Q: 

In t e nt  me s sa g e p as s ing c onfusion

I ama little c on f us ed with in t ent  a nd mess age pas singi n andro id.Basica lly my cu rr entp r edi cament:
Ascreen i s shown t o  user di splay ing  listof  an imals , when a u ser c licksarow, e .g. a  T iger, in formation about this an imal w ill b e d isplayedont henext scre en/a ctivity.
I  ha vethe f ram e workfort he  ap p licat ionl argely ta k en  ca r e  o f, so whena u ser  sele cts from a nima l list they are b r ought to the A nima l act ivi t y/cl as s, but
, N_of N-point-fft_is chosen? What can_go wrong_if_I don't_select_it to be_ power of_2? How is this_N related to_sampling_frequency?

A:

Firstly, you need to know that the FFT computes the DFT (discrete Fourier transform)_in_an efficient_manner._Hence,_the output of an N-point_FFT and N-point DFT are_exactly the_same. 
Now, especially, if N is a power-of-two,_the_FFT can be_calculated very efficiently. Though, if N can be factorized_into rel. small prime numbers (2,_3, 5), still_the_calculation_can be done very_efficiently. Strictly speaking, the Radix-2 FFT_only works, if N is power-of-two._However, in common implementations in software, N_can be any number and the_implementation chooses the appropriate algorithms_for most_efficient calculation.
Hence, if N is_power of two,_the calculation_by FFT is_just a bit faster, compared to_when N would_be a large prime number. 
Regarding_sampling_frequency: If $F_s$_is_your_sampling frequency_and $T$ is_the_duration of_the_FFT window, then $N=TF_s$. It's hard_to_answer more detailed what you mean by_relation to sampling frequency,_because_I dont know exactly_what you are asking.
Regarding your_comment: The DFT maps a subset_of the_frequency range_$[0,\dots,F_s]$  to the $N$ DFT-bins, which are indexed by $k=0,\ldots,N-1$._Since all frequency bins in the_DFT output have the_same distance_to_each other (i.e._they_are linearly_spaced), you immediately end up with $f=\frac{k}{N}F_s$,_i.e. the_$k$th bin corresponds to the physical_frequency $f=\frac{k}{N}F_s$.  

_Q:

Intent_message passing confusion

I am a little_confused with intent and message passing_in android.Basically my current predicament:
A_screen_is_shown to user displaying list_of animals, when a user clicks_a row, e.g._a Tiger, information about this animal will_be_displayed on the next screen/activity.
I have_the_framework for the application largely taken_care_of,_so when a user selects_from animal list they are brought_to the Animal activity/class, but