function z = zernpol(n,m,r,nflag) /}iBrMD{[
%ZERNPOL Radial Zernike polynomials of order N and frequency M. ;vbMC74J#
% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of 6Ypc]ym=J
% order N and frequency M, evaluated at R. N is a vector of oq|`;k
% positive integers (including 0), and M is a vector with the 8!@}\6qM
% same number of elements as N. Each element k of M must be a d>Nh<PqH6
% positive integer, with possible values M(k) = 0,2,4,...,N(k) c6y>]8_
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is <P@O{Xi+K
% a vector of numbers between 0 and 1. The output Z is a matrix o02G:!gB
% with one column for every (N,M) pair, and one row for every vo2GFo
% element in R. |WfL'_?$
% ~[~#PO
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- hb
%F"Q
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is c%(Ndi
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to c++q5bg@)
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 8#o2 qQ2+
% for all [n,m]. [F(iV[n%
% /E i e5p
% The radial Zernike polynomials are the radial portion of the og&h$<uOZt
% Zernike functions, which are an orthogonal basis on the unit 4x@W]*i
% circle. The series representation of the radial Zernike \'iy(8i
% polynomials is ` K0PLxSv
% %Z,n3iND
% (n-m)/2 v(Sh+p
% __ D(&WEmm\B
% m \ s n-2s t~) g)=>
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r PAxR?2m{
% n s=0 U3 UA
% /^bU8E&^M
% The following table shows the first 12 polynomials. >J_P[v
% ya,-Lt
% n m Zernike polynomial Normalization |`{$Ego:
% --------------------------------------------- Q~P|=*
% 0 0 1 sqrt(2) y7GgTC/H
% 1 1 r 2 IY
mkZ?cW
% 2 0 2*r^2 - 1 sqrt(6) qElPYN*wF
% 2 2 r^2 sqrt(6) 6\-u:dvGI?
% 3 1 3*r^3 - 2*r sqrt(8) '
~fP#y
% 3 3 r^3 sqrt(8) jpoNTl'
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) G|"m-.9F
% 4 2 4*r^4 - 3*r^2 sqrt(10) D]|{xK C}
% 4 4 r^4 sqrt(10) UdA,.C0
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) |L:X$oM
% 5 3 5*r^5 - 4*r^3 sqrt(12) "ctZ"*
% 5 5 r^5 sqrt(12) 4T
v=sP
% --------------------------------------------- (NJ.\m
% q9a6s{,
% Example: U)Tl<l<
% jc#gn&4C
% % Display three example Zernike radial polynomials =En1?3?
% r = 0:0.01:1; Ae"|a_>fMI
% n = [3 2 5]; 3a=\$x@
% m = [1 2 1]; #YK3Ogb,
% z = zernpol(n,m,r); mQ:YHtHE.F
% figure t=s.w(3t
% plot(r,z) |+>U91!
% grid on yUO%@;
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') b@K1;A! S
% R|wS*xd ,
% See also ZERNFUN, ZERNFUN2. Gm0}KU
@,]W
% A note on the algorithm. && PZ;
% ------------------------ 2+g'ul`
% The radial Zernike polynomials are computed using the series \$F#bIjC
% representation shown in the Help section above. For many special *O)i)["
% functions, direct evaluation using the series representation can W`TSR?4~t?
% produce poor numerical results (floating point errors), because u),.q7(m
% the summation often involves computing small differences between &0J8ICd=
% large successive terms in the series. (In such cases, the functions %[azMlp<
% are often evaluated using alternative methods such as recurrence N%e^2O)
% relations: see the Legendre functions, for example). For the Zernike s vS)7]{cU
% polynomials, however, this problem does not arise, because the 7m?fvKy
% polynomials are evaluated over the finite domain r = (0,1), and CteNJBm
% because the coefficients for a given polynomial are generally all [8oX[oP
% of similar magnitude. r>CBp$
% ua_,c\iL
% ZERNPOL has been written using a vectorized implementation: multiple "s(|pQh;
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] (*V!V3E3#
% values can be passed as inputs) for a vector of points R. To achieve av:%wJUl,$
% this vectorization most efficiently, the algorithm in ZERNPOL IMzt1l
=7
% involves pre-determining all the powers p of R that are required to 3 +`,'Q9
% compute the outputs, and then compiling the {R^p} into a single S?VKzVDB.S
% matrix. This avoids any redundant computation of the R^p, and ;z+}|>!
% minimizes the sizes of certain intermediate variables. :
Cli8#
% A6
% Paul Fricker 11/13/2006 X gtn}7N.
F"3'~6
6q
`Un}
% Check and prepare the inputs: jyidNPLm4
% ----------------------------- C 20VSwd
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) ;sz _W%-;@
error('zernpol:NMvectors','N and M must be vectors.') [MKt\(
end 4E1j0ARQQ
R"\(a
if length(n)~=length(m) Ub4)x
error('zernpol:NMlength','N and M must be the same length.') K5??WB63B
end Ea0EG>Y
t? =V<Yd1
n = n(:); 7vI
ROK~
m = m(:); ~~I]SI k{
length_n = length(n); Ay%]l| Gm
_.%g'=14f
if any(mod(n-m,2)) ~*Y/#kPY
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') P*hYh5a
end h53G$Ol.
<dz_7hR"
if any(m<0) f2v~: u
error('zernpol:Mpositive','All M must be positive.') 54RexB o
end O<dCvH
47A[-&y*X
if any(m>n) =CCddLO
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') O~6AX)|&=
end (/t{z=
LJt5?zQKrW
if any( r>1 | r<0 ) f}?pY"yvO
error('zernpol:Rlessthan1','All R must be between 0 and 1.') y
S<&d#:"
end r'XWt]B+[
7ks!0``
if ~any(size(r)==1) 3Gw*K-.
error('zernpol:Rvector','R must be a vector.') Q^?$2ck=
end JxM32?Rm*w
'gsO}xj
r = r(:); A-$C6q
length_r = length(r); -Q ];o~
RL/5o"
if nargin==4 hl DU.k
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); L[Wi[S6=)g
if ~isnorm y\dx \
error('zernpol:normalization','Unrecognized normalization flag.') ]2|KG3t
end ]J/;Xp
else 4e?c W&
isnorm = false; ^nQJo"g\
end wGHVq
fm5
&rc
r>-
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% {~ w!
% Compute the Zernike Polynomials ?;w\CS^Qu
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Dr}elR>~G=
Cwji,*
% Determine the required powers of r: (@O,U
% ----------------------------------- [:A">eYI
rpowers = []; tM;+U
for j = 1:length(n) +|4olK$[
rpowers = [rpowers m(j):2:n(j)]; \oP
end {%\;'&@z\
rpowers = unique(rpowers); eV0eMDY5
&@PAv5iNf
% Pre-compute the values of r raised to the required powers, QP@@h4J^
% and compile them in a matrix: s;tI?kR>%
% ----------------------------- |UcF%VNnz1
if rpowers(1)==0 G2:.8ok
rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); 1d&Q
E\2}
rpowern = cat(2,rpowern{:}); Fg2/rC:_
rpowern = [ones(length_r,1) rpowern]; Y&i&H=U
else NpA%7Q~B$,
rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); GB6(WAmr
rpowern = cat(2,rpowern{:}); |Y2n6gkH[
end s:tWEgZk?
Z_T~2t
% Compute the values of the polynomials: GzT?I
7|M
% -------------------------------------- /[q_f
z = zeros(length_r,length_n); +bWo{
for j = 1:length_n 1O90 ]c0
s = 0:(n(j)-m(j))/2; qJXfc||Zg
pows = n(j):-2:m(j); iciRlx.$c
for k = length(s):-1:1 t
Q>/1
p = (1-2*mod(s(k),2))* ... KXu1%`x=%Z
prod(2:(n(j)-s(k)))/ ... (W9 K:]}
prod(2:s(k))/ ... 1}CJ&
prod(2:((n(j)-m(j))/2-s(k)))/ ... !~-@sq
prod(2:((n(j)+m(j))/2-s(k))); mx2Ov u
idx = (pows(k)==rpowers); 4 %u\dTg/B
z(:,j) = z(:,j) + p*rpowern(:,idx); ,JJ1sf2A
end AJP-7PPD
of`WP
if isnorm uU+?:C
z(:,j) = z(:,j)*sqrt(2*(n(j)+1)); 2d&HSW
end g{m~TVm'
end m`@~ZIa?>B
C{V,=Fo^
% EOF zernpol