function z = zernpol(n,m,r,nflag) u teI[Q
%ZERNPOL Radial Zernike polynomials of order N and frequency M. {}TR'Y4
% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of 3#@ETt0X(
% order N and frequency M, evaluated at R. N is a vector of zXH CP.Rmg
% positive integers (including 0), and M is a vector with the zFtRsa5+
% same number of elements as N. Each element k of M must be a I8 \Ka=w
% positive integer, with possible values M(k) = 0,2,4,...,N(k) aH1mW;,1u
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is 4LBMhLy
% a vector of numbers between 0 and 1. The output Z is a matrix BEv>?T
0
% with one column for every (N,M) pair, and one row for every l'2a?1/q
% element in R. f/:XIG
% 2nFSu9}+r
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- 9V%s1@K
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is j+c<0,Kj
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to ~Z'3(n*9
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 PB :Lj
% for all [n,m]. ~X/1%
% .d;XLS~
% The radial Zernike polynomials are the radial portion of the IaU
% Zernike functions, which are an orthogonal basis on the unit hl[!4#b]K
% circle. The series representation of the radial Zernike U&D"fM8
% polynomials is YAIDSZ&l[
% Xh,{/5m
% (n-m)/2 W:7oGZ>4
% __ L.[ H
% m \ s n-2s wv2
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r SY`
U]-h
% n s=0 }/yhwijg
% OgiElA.
% The following table shows the first 12 polynomials. aIv>X@U}
% McgTTM;E
% n m Zernike polynomial Normalization 3+<}Hm+
% --------------------------------------------- T<|B1jA
% 0 0 1 sqrt(2) Wb] ha1$
% 1 1 r 2 u6AReL'f
% 2 0 2*r^2 - 1 sqrt(6) jB*%nB*x
% 2 2 r^2 sqrt(6) S=>54!{`x
% 3 1 3*r^3 - 2*r sqrt(8) ;[]{O5TB
% 3 3 r^3 sqrt(8) [<Wo7G1s
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) iw\RQ
0
% 4 2 4*r^4 - 3*r^2 sqrt(10) coHzbD~#H
% 4 4 r^4 sqrt(10) +s:!\(BM
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) " r!O9X6
% 5 3 5*r^5 - 4*r^3 sqrt(12) 1 f ]04TI
% 5 5 r^5 sqrt(12) Cg/L/0Ak
% --------------------------------------------- !F*7Mif_E
% WHQg6r
% Example: ca@0?q#
% *.0}3
% % Display three example Zernike radial polynomials F$UvYy4O d
% r = 0:0.01:1; /vi>@a
% n = [3 2 5]; J#7\R':}zl
% m = [1 2 1]; bwG2=
% z = zernpol(n,m,r); :?s~,G_*l
% figure _ cK"y2
% plot(r,z) H 3YFbR
% grid on 05mjV6j7m
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') ?GPTJ#=j=]
% sr+*
q6W
% See also ZERNFUN, ZERNFUN2. s
l|n]#)
5:%xuJD
% A note on the algorithm.
C9[Jr)QX
% ------------------------ k/A8|
% The radial Zernike polynomials are computed using the series @vdBA hXk
% representation shown in the Help section above. For many special =EI>@Y"
% functions, direct evaluation using the series representation can GsG.9nd
% produce poor numerical results (floating point errors), because Z,%^BAJ
% the summation often involves computing small differences between D<5;4Mb
% large successive terms in the series. (In such cases, the functions \jDD=ew
% are often evaluated using alternative methods such as recurrence I@a y&NNh
% relations: see the Legendre functions, for example). For the Zernike i>YD_#w
% polynomials, however, this problem does not arise, because the M=$
qus
% polynomials are evaluated over the finite domain r = (0,1), and +:3K?G-
% because the coefficients for a given polynomial are generally all o(GXv3L
% of similar magnitude. nFU'DZ
% JsohhkJNGi
% ZERNPOL has been written using a vectorized implementation: multiple 3-z;pk
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] {3F;:%$`c
% values can be passed as inputs) for a vector of points R. To achieve 3 f=_F
% this vectorization most efficiently, the algorithm in ZERNPOL ?.d6!vA
% involves pre-determining all the powers p of R that are required to wQ
/IT}-
% compute the outputs, and then compiling the {R^p} into a single 1zwk0={x-%
% matrix. This avoids any redundant computation of the R^p, and r>4HF"Nm
% minimizes the sizes of certain intermediate variables. YqhZndktX
% dWbSrl
% Paul Fricker 11/13/2006 (_h<<`@B
DPCB=2E
J jRz<T;
% Check and prepare the inputs: qPeaSv]W
% ----------------------------- \ vj<9ke&
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) -`nQa$N-
error('zernpol:NMvectors','N and M must be vectors.') .{[+d3+,
end (}ObX!,
.)L%ANf
if length(n)~=length(m) "mlVs/nsyG
error('zernpol:NMlength','N and M must be the same length.') ZbVo<p5* ]
end IE7%u92
32nB9[l
n = n(:); S B2R
m = m(:); Ws%@SK
length_n = length(n); 28,Hd!{
-]$q8Q(hM
if any(mod(n-m,2)) B:Y"X:Y
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') KE>|,Ur
end
WWf#in
oYOR%'0*m+
if any(m<0) Qh*"B
error('zernpol:Mpositive','All M must be positive.') ]-ad\PI$
end }8
V/Cd9
/4Ud6gscf
if any(m>n) mX8k4$z
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') .g/PWEr\I
end L@9@3?
M_
* KA
if any( r>1 | r<0 ) ykAZP[^'
error('zernpol:Rlessthan1','All R must be between 0 and 1.') zt&"K0X|
end &CP]+ at
gY!+x=cx0
if ~any(size(r)==1) %?<Y&t
error('zernpol:Rvector','R must be a vector.') `"@Pr,L
end <}Hfu-PLo
4FwtC"G3
r = r(:); i2bkgyzB.
length_r = length(r); }6S~"<Ym
h{ xq
if nargin==4 :Vdo.uUa
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); PB[Y^q
if ~isnorm iO$Z?Dyg9
error('zernpol:normalization','Unrecognized normalization flag.') Bs?B\k=
end 3m;*gOLk6
else "XKcbdr8-
isnorm = false; || p>O
end MS Qz,nn
YCBp]xuE
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ]lQLA
IQ
% Compute the Zernike Polynomials W20qn>{z
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% XC*!=h*
76IjM4&a
% Determine the required powers of r: IA6,P>}N
% ----------------------------------- 62s0$vw
rpowers = []; T:<mme3v
for j = 1:length(n) [hhPkJf|f
rpowers = [rpowers m(j):2:n(j)]; T)CEcz
end y)//u:l
rpowers = unique(rpowers); -F->l5
ta;q{3fe
% Pre-compute the values of r raised to the required powers, 0,{tBo
% and compile them in a matrix: OYYk[r
% ----------------------------- Ca]V%g(
if rpowers(1)==0 7Be\^%
rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); [D$%LR X
rpowern = cat(2,rpowern{:}); (Ts#^qC
rpowern = [ones(length_r,1) rpowern]; Jxo#sV-
else "|,;~k1
rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); A_pcv7=@
rpowern = cat(2,rpowern{:}); v)c[-:"z
end BN]{o(EB
>Hd Pcsl L
% Compute the values of the polynomials: AQ<2 "s
% -------------------------------------- *K#Ci1Q
z = zeros(length_r,length_n); gH
u!~l
for j = 1:length_n -|cB7P
s = 0:(n(j)-m(j))/2; 7g%.:H=
pows = n(j):-2:m(j); (@(rz/H
for k = length(s):-1:1 'Dx_n7&=
p = (1-2*mod(s(k),2))* ... h0c&}kM
prod(2:(n(j)-s(k)))/ ... `VL<pqPP
prod(2:s(k))/ ... TBU.%3dEyI
prod(2:((n(j)-m(j))/2-s(k)))/ ... 0}4FwcCr\
prod(2:((n(j)+m(j))/2-s(k))); mo*ClU7
idx = (pows(k)==rpowers); KQulz
z(:,j) = z(:,j) + p*rpowern(:,idx); UmNh0nS
end "k>;K,:
1cdX0[sN
if isnorm -<Oy5N
z(:,j) = z(:,j)*sqrt(2*(n(j)+1)); w+Oo-AGNH
end gPf^dGi7t
end 8]2j*e0xV
~i5t1
% EOF zernpol