function z = zernpol(n,m,r,nflag) YB1Jv[
%ZERNPOL Radial Zernike polynomials of order N and frequency M. hTQ8y10a
% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of fuU
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% order N and frequency M, evaluated at R. N is a vector of - -\eYVh[
% positive integers (including 0), and M is a vector with the N*f]NCSi
% same number of elements as N. Each element k of M must be a dsn(h5,Q'
% positive integer, with possible values M(k) = 0,2,4,...,N(k) _;,"!'R`f
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is d%K&
% a vector of numbers between 0 and 1. The output Z is a matrix }` YtXD-o
% with one column for every (N,M) pair, and one row for every mX%T"_^
% element in R. TQtHU6
% Iqci}G%r
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- Nwo*tb:
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is rvacCwI
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to \S_Ae;
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 >K<cc#Aa
% for all [n,m]. 3a[ LM!
% rJ{k1H >
% The radial Zernike polynomials are the radial portion of the ]XASim:A
% Zernike functions, which are an orthogonal basis on the unit R7 rO7M!
% circle. The series representation of the radial Zernike "rrw~
% polynomials is ]K'OH&
% n?>|2>
% (n-m)/2 /:v}Ni"6nF
% __ &]tm'N25
% m \ s n-2s 1En:QQ4/
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r :NL[NbQYt
% n s=0 0 ;].q*|#
% h1)ny1;
% The following table shows the first 12 polynomials. /
*/"gz%
% V,%K"b=
% n m Zernike polynomial Normalization QUm[7<"
% --------------------------------------------- icQQLSU5
% 0 0 1 sqrt(2) rp4{lHw>C/
% 1 1 r 2 P:WxhO/
% 2 0 2*r^2 - 1 sqrt(6) RG=i74a
% 2 2 r^2 sqrt(6) $o.;}
% 3 1 3*r^3 - 2*r sqrt(8) )gD2wk(
% 3 3 r^3 sqrt(8) dOK]Su
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) a)*(**e$*i
% 4 2 4*r^4 - 3*r^2 sqrt(10) lvRTy|%[
% 4 4 r^4 sqrt(10) 2r!- zEV
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) *+k
yuY J
% 5 3 5*r^5 - 4*r^3 sqrt(12) @
M4m!;rM
% 5 5 r^5 sqrt(12) +^jm_+
% --------------------------------------------- ^ p7z3ng
% p({Lp}'
% Example: w5yX~8UzJ
% 505ejO|
% % Display three example Zernike radial polynomials K"[\)&WBG
% r = 0:0.01:1; 8;"9A
% n = [3 2 5]; iJeodfC
% m = [1 2 1]; dq%C~j{v
% z = zernpol(n,m,r); x+TdTe;p
% figure %O!TS_~9
% plot(r,z) Xy. /1`X
% grid on yVQW|D0,j
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') &grvlK
% >4q6
% See also ZERNFUN, ZERNFUN2. E#3tkFF0Z[
#k1IrqUp
% A note on the algorithm. t%O)Ti
% ------------------------ b@Dt]6_UL
% The radial Zernike polynomials are computed using the series R)4,f~@"
% representation shown in the Help section above. For many special ?p/}eRgi
% functions, direct evaluation using the series representation can DAg*
% produce poor numerical results (floating point errors), because Pe-rwM
% the summation often involves computing small differences between cq 5^7.
% large successive terms in the series. (In such cases, the functions mfF `K2R
% are often evaluated using alternative methods such as recurrence x}O,xquY
% relations: see the Legendre functions, for example). For the Zernike cs_
% polynomials, however, this problem does not arise, because the TyA1Qk\
% polynomials are evaluated over the finite domain r = (0,1), and *2}f $8
% because the coefficients for a given polynomial are generally all +J~%z*A
% of similar magnitude. >$yA
,N
% :xTm-L
% ZERNPOL has been written using a vectorized implementation: multiple o~W,VhCP
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] B'mUDW8\D
% values can be passed as inputs) for a vector of points R. To achieve k
]T
% this vectorization most efficiently, the algorithm in ZERNPOL azNv(|eeJL
% involves pre-determining all the powers p of R that are required to (`_fP.Ogb
% compute the outputs, and then compiling the {R^p} into a single yye5GVY$
% matrix. This avoids any redundant computation of the R^p, and 2#00<t\
% minimizes the sizes of certain intermediate variables. z,hBtq:-$
% Qg]A^{.1
% Paul Fricker 11/13/2006 -E3cS
uix/O*^
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% Check and prepare the inputs: ,t;US.s([.
% ----------------------------- *0?@/2&
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) /2hRLyeAZ
error('zernpol:NMvectors','N and M must be vectors.') ^16zZ*
end ycwkF$7
fYzP4
if length(n)~=length(m) o2hk!#5[4
error('zernpol:NMlength','N and M must be the same length.') 3IjsV5a
end Vy| 4k2
s? Xgo&rS_
n = n(:); : 2$*'{mM
m = m(:); ?=^\kXc[
length_n = length(n); VXlAK(
ho B[L}<c
if any(mod(n-m,2)) BX6kn/i
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') Hq,@j{($
end ,!LY:pMK
'\+"3!$
if any(m<0) fLd2{jI,
error('zernpol:Mpositive','All M must be positive.') H3`.Y$z
end |W$|og'wC
2_6ON
if any(m>n) qX; F+~
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') _ WPt
zL
end \x\N?$`ANc
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if any( r>1 | r<0 ) 80T2EN:$
error('zernpol:Rlessthan1','All R must be between 0 and 1.') kM1N4N7
end (fr=N5
_h1eW9q
if ~any(size(r)==1) "wg$ H1K
error('zernpol:Rvector','R must be a vector.') h^qZi@L
end : vx<m_
Q$ Dx:
r = r(:); A%7f;&x!
length_r = length(r); Iu~<Y(8^q#
V82I%gPF
if nargin==4 "frioi`a2
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); wHQ$xO;vD'
if ~isnorm =J]EVD
error('zernpol:normalization','Unrecognized normalization flag.') 4zt:3bWU
end D/ sYH0.V$
else z}.6yHS
isnorm = false; 4\p%|G^hU
end JR
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% /988K-5k
% Compute the Zernike Polynomials W,[QK~
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% H?M:<q0|G
GCiG50Z=
% Determine the required powers of r: fA?v\'Qq/
% ----------------------------------- V/#J>-os}W
rpowers = []; 2<p@G#(
for j = 1:length(n) aaw[ia_E L
rpowers = [rpowers m(j):2:n(j)]; vu91"
4Fa
end TXXG0 G
rpowers = unique(rpowers); s :BW}PM
@1gURx&2_
% Pre-compute the values of r raised to the required powers, yzT1Zg_ER
% and compile them in a matrix: frDMFEXXP
% ----------------------------- *| W*Mu
if rpowers(1)==0 -$:*!55:j
rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); $w <R".4
rpowern = cat(2,rpowern{:}); <_Z.fdUA
rpowern = [ones(length_r,1) rpowern]; |r,})o>
else jb,a>9]p
rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); p~=z)7%e'
rpowern = cat(2,rpowern{:}); E8"&gblg
end Im!b-1
Bos}
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% Compute the values of the polynomials: 2#3`[+g<n
% -------------------------------------- V_D wHq2
z = zeros(length_r,length_n); =EM<LjO
for j = 1:length_n G3+e5/0
s = 0:(n(j)-m(j))/2; ts@Z5Yw*!
pows = n(j):-2:m(j); tc)Md]S
for k = length(s):-1:1 im9EV|;
p = (1-2*mod(s(k),2))* ... k\;D;e{
prod(2:(n(j)-s(k)))/ ... +r//8&
prod(2:s(k))/ ... T+zhj++
prod(2:((n(j)-m(j))/2-s(k)))/ ... aXQAm$/
>
prod(2:((n(j)+m(j))/2-s(k))); $gz8!
f?
idx = (pows(k)==rpowers); GD
d'{qE6
z(:,j) = z(:,j) + p*rpowern(:,idx); =q)+_@24>d
end z;2& d<h
vO&X<5?Qc
if isnorm \9tJ/~
z(:,j) = z(:,j)*sqrt(2*(n(j)+1)); V9}\0joM
end rr\9HA
end %mU$]^Tw(
2-N7%]h
% EOF zernpol