function z = zernpol(n,m,r,nflag) EoWzHa
%ZERNPOL Radial Zernike polynomials of order N and frequency M. ;QD;5
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% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of P,=J"%a -
% order N and frequency M, evaluated at R. N is a vector of =C1Qo#QQ%
% positive integers (including 0), and M is a vector with the }mZ*f y0t
% same number of elements as N. Each element k of M must be a jt?%03iuk
% positive integer, with possible values M(k) = 0,2,4,...,N(k) ,?~,"IQyi[
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is
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% a vector of numbers between 0 and 1. The output Z is a matrix GhA~Pj ZS
% with one column for every (N,M) pair, and one row for every Vzm7xl [
% element in R. 2DdLqZY#
% 9gayu<J
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- ~x|Sv4M
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is )W JI=jl
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to 4>`w9
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 *X5LyO3-gP
% for all [n,m]. 3PeJPw
% 4zbV' ]
% The radial Zernike polynomials are the radial portion of the uW_ /7ex
% Zernike functions, which are an orthogonal basis on the unit S^=/}PT'
% circle. The series representation of the radial Zernike $&
gidz/w
% polynomials is <QLj6#d7Y
% NH6!|T
% (n-m)/2 ~3]8f0^%m
% __ n:z>l,`C]
% m \ s n-2s !gQ(1u|r
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r I65GUX#DV
% n s=0 :b)@h|4
% iAhRlQ{Qu
% The following table shows the first 12 polynomials. 1H@F>}DP
% 3e1"5~?'<
% n m Zernike polynomial Normalization dU n#'<g5
% --------------------------------------------- o62gLO]z@
% 0 0 1 sqrt(2) <-7Ha_#
% 1 1 r 2 .AS,]*?Zn%
% 2 0 2*r^2 - 1 sqrt(6) )A;<'{t #L
% 2 2 r^2 sqrt(6) =J\7(0Dz4t
% 3 1 3*r^3 - 2*r sqrt(8) -W vAmi
% 3 3 r^3 sqrt(8) U?yXTMD
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) n&&y\?n
% 4 2 4*r^4 - 3*r^2 sqrt(10) ?q`mr_x%?
% 4 4 r^4 sqrt(10) M!@[lJ
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) uS.a9
Q(
% 5 3 5*r^5 - 4*r^3 sqrt(12)
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% 5 5 r^5 sqrt(12) l).Ijl}AH;
% --------------------------------------------- %&GQ]pmcY
% l>q.BG
% Example: kp"cHJNx
% FiL
JF!
% % Display three example Zernike radial polynomials /m:}rD
% r = 0:0.01:1; VQ`O;n6/`
% n = [3 2 5]; oaE3Aa
% m = [1 2 1]; !{\c`Z<#
% z = zernpol(n,m,r); U {v_0\ES
% figure "WL
% plot(r,z) vS<e/e+
% grid on %VZ\4+8S
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') L.[2l Q
% ' 'N@ <|
% See also ZERNFUN, ZERNFUN2. @^@-A\7[KO
E ..[F<5
% A note on the algorithm. c8MNo'h
% ------------------------ \GPc_m:qL
% The radial Zernike polynomials are computed using the series Atw^C+"vW&
% representation shown in the Help section above. For many special =r8(9:F!
% functions, direct evaluation using the series representation can 54&2SU$kx
% produce poor numerical results (floating point errors), because Joj8'
% the summation often involves computing small differences between j>zVC;Sj*
% large successive terms in the series. (In such cases, the functions '@bA_F(
% are often evaluated using alternative methods such as recurrence 2{\Y<%.
% relations: see the Legendre functions, for example). For the Zernike 2(|V1]6D?
% polynomials, however, this problem does not arise, because the [g_@<?zg
% polynomials are evaluated over the finite domain r = (0,1), and g!UM8I-$
% because the coefficients for a given polynomial are generally all c$;enAf@
% of similar magnitude. -Zh+5;8g
% ap!<8N
% ZERNPOL has been written using a vectorized implementation: multiple !bg3
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] C+j+q648>
% values can be passed as inputs) for a vector of points R. To achieve up?8Pq*
% this vectorization most efficiently, the algorithm in ZERNPOL |v&&%>A2
% involves pre-determining all the powers p of R that are required to xPv&(XZR
% compute the outputs, and then compiling the {R^p} into a single ?a}~yz#B(
% matrix. This avoids any redundant computation of the R^p, and czzV2P/t}
% minimizes the sizes of certain intermediate variables. 3z<t#
% Oh: -Y]m=
% Paul Fricker 11/13/2006 ohl%<FqS
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!+(n
-XBNtM_"
% Check and prepare the inputs: 2ou?:5i
% ----------------------------- %JZIg!
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) 7E'C o|
error('zernpol:NMvectors','N and M must be vectors.') I{$|Ed1
end *`W82V
f &|SGD*
if length(n)~=length(m) f$L5=V
error('zernpol:NMlength','N and M must be the same length.') lbY>R@5
end |(N4x(xl
_)Ms9RN
n = n(:); Z3d&I]Tf
m = m(:); {*m?t 7
length_n = length(n); Q=[&~^Y)
mAMKCxz,
if any(mod(n-m,2)) lF<(yF5
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') j:#[voo7
end +^.(3Aw
Tm `CA0@
if any(m<0) 03xQ%"TU<
error('zernpol:Mpositive','All M must be positive.') %K%z<R8
end %`~8j H@
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if any(m>n) bm^ou#]|
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') "6ZatRUd
end cX2b:
'*pq@|q;t
if any( r>1 | r<0 ) P*}Oi7Z
error('zernpol:Rlessthan1','All R must be between 0 and 1.') :V
[vE h
end D 6(w}W
D_{J:Hb
if ~any(size(r)==1) pD{Li\LY
error('zernpol:Rvector','R must be a vector.') n\QG-?%Pi
end C$_H)I
.R1)i-^
r = r(:); zr,jaR;
length_r = length(r); /{lls2ycW%
+um;
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if nargin==4 jooh`| `P
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); |Q{ l]D
if ~isnorm 0-@waK
error('zernpol:normalization','Unrecognized normalization flag.') 49CMRO,T
end r6A7}v
else iU &V}p
isnorm = false; OS3J,f}<=
end PiN3t]2
tqHXzmsjW
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |YH1q1l
% Compute the Zernike Polynomials sbRg=k&Ns
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Yd@9P2C
<1"6`24
% Determine the required powers of r: 6ik6JL$AI
% ----------------------------------- GovGh? X#x
rpowers = []; 8!1o,=I$
for j = 1:length(n) 7|2:;5:U
rpowers = [rpowers m(j):2:n(j)]; 1vobfZ-w9
end X/@Gx 4
rpowers = unique(rpowers); hM;E UWv
wc;5tb#
% Pre-compute the values of r raised to the required powers, <4Ak$E%"
% and compile them in a matrix: XVY^m}pMe
% ----------------------------- i22R3&C
if rpowers(1)==0 Ouj5NL
rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); ct/I85c@P
rpowern = cat(2,rpowern{:}); __zsrIUJ
rpowern = [ones(length_r,1) rpowern]; R (6Jvub"I
else #0weN%
rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); 7UMsKE-
rpowern = cat(2,rpowern{:}); p.zU9rID
end ?g9CeeH*
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