function z = zernpol(n,m,r,nflag) N|EH`eu^i
%ZERNPOL Radial Zernike polynomials of order N and frequency M. qPK3"fzH
% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of -o#HO_9
% order N and frequency M, evaluated at R. N is a vector of AF g*
% positive integers (including 0), and M is a vector with the JV=d!Gi[C
% same number of elements as N. Each element k of M must be a UQgOtqL3
% positive integer, with possible values M(k) = 0,2,4,...,N(k) , |CT|2D>
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is &~ QQZ]q6
% a vector of numbers between 0 and 1. The output Z is a matrix 6UXa
5t
% with one column for every (N,M) pair, and one row for every In#V1[io
% element in R. D^W6Cq5\
% x]&V7Y
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- ;Oh4W<hH}
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is aT$q1!U`j2
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to 9JV(}v5[
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 x48Y#"'
% for all [n,m]. 6?b9~xRW
% ;Y5"[C9|
% The radial Zernike polynomials are the radial portion of the L']EYK5
% Zernike functions, which are an orthogonal basis on the unit 7^P!@o$v!
% circle. The series representation of the radial Zernike zA=gDuy3@
% polynomials is }A3(g$8KR
% =|O`al
% (n-m)/2 9!zUv:;
% __ #80DM
% m \ s n-2s q$`{$RX
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r O'{UAb+-
% n s=0 /PH+K24v~
% i% 19|an
% The following table shows the first 12 polynomials. -H5n>j0!{
% 2qLRcA=R
% n m Zernike polynomial Normalization fEf",{I
% --------------------------------------------- h4N!zj[
% 0 0 1 sqrt(2) uF_gfjR[m
% 1 1 r 2 rT9<_<
% 2 0 2*r^2 - 1 sqrt(6) )F4H'
% 2 2 r^2 sqrt(6) x a#0y
% 3 1 3*r^3 - 2*r sqrt(8) ;A7HEx
% 3 3 r^3 sqrt(8) Aq@_^mq1A
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) Sr Z\]
% 4 2 4*r^4 - 3*r^2 sqrt(10) 3CK4a,]Dm
% 4 4 r^4 sqrt(10) Oaf!\z}
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) >MZWm6M8
% 5 3 5*r^5 - 4*r^3 sqrt(12) teH $hd-q
% 5 5 r^5 sqrt(12) s1.YH?A;
% --------------------------------------------- 0i/l2&x*k]
% ]CsF} wr'z
% Example: E,&BP$B
% 0(\ybppx
% % Display three example Zernike radial polynomials g
N76
% r = 0:0.01:1; 9r=@S
% n = [3 2 5]; "W$,dWF
% m = [1 2 1]; 0j\?zt?
% z = zernpol(n,m,r); W}p>jP}
% figure `p1szZD&
% plot(r,z) :bFCnV`Q
% grid on v1%rlP
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') )/kkvI()l
% ]4wyuP,up
% See also ZERNFUN, ZERNFUN2. &^$dHr6v
vJ9Uw
% A note on the algorithm. ~&B{"d
% ------------------------ N)|mA)S)
% The radial Zernike polynomials are computed using the series w=5 D>]
% representation shown in the Help section above. For many special u&Ts'j
% functions, direct evaluation using the series representation can ,DsqKXSU
% produce poor numerical results (floating point errors), because +>mbBu!7
% the summation often involves computing small differences between m`CcU`s
% large successive terms in the series. (In such cases, the functions U/'"w
v1y
% are often evaluated using alternative methods such as recurrence GADb Xp3
% relations: see the Legendre functions, for example). For the Zernike )\#w=P
% polynomials, however, this problem does not arise, because the +M-x*;.
% polynomials are evaluated over the finite domain r = (0,1), and |;3Ru vX?+
% because the coefficients for a given polynomial are generally all Q-o}Xnj*!L
% of similar magnitude. ; mnV)8:F
% 'X&sH/>r
% ZERNPOL has been written using a vectorized implementation: multiple lj0"2@z3"E
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] (PAkKY}
% values can be passed as inputs) for a vector of points R. To achieve dx}) 1%
% this vectorization most efficiently, the algorithm in ZERNPOL !wy
Qk
% involves pre-determining all the powers p of R that are required to ~Z-M?8:
% compute the outputs, and then compiling the {R^p} into a single 7pH`"$
% matrix. This avoids any redundant computation of the R^p, and )jkX&7x
% minimizes the sizes of certain intermediate variables. 1Q1NircJ
% dU%Q=r8R
% Paul Fricker 11/13/2006 IGz92&y
Im7<\ b@
eaLSq
% Check and prepare the inputs: JW[y
% ----------------------------- 6)63Yp(
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) >PdYQDyVS
error('zernpol:NMvectors','N and M must be vectors.') z%-Yz-G9
end P__JN\{9
QCB2&lN\&L
if length(n)~=length(m) L1=+x^WQ
error('zernpol:NMlength','N and M must be the same length.') xL8r'gV@
end 2z9\p%MX
|hBX"
n = n(:); h8@8Qw
m = m(:); I^erMQn[ z
length_n = length(n); q
SR\=:$
C
"XvspJ
if any(mod(n-m,2)) $D{KXkrd
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') H]&a}WQ_
end G"w
?{W@
+oa\'.~?
if any(m<0)
1@Abs
error('zernpol:Mpositive','All M must be positive.') gzfs9e
end xCU^4DO3p
ZC}'! $r7
if any(m>n) Y_m/? [:
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') wh4ik`S 1
end 48;6C g
}
IJ
if any( r>1 | r<0 ) {A2EGUmF2
error('zernpol:Rlessthan1','All R must be between 0 and 1.') $|+q9o\
end #ra"(/)
]WlE9z7:8
if ~any(size(r)==1) HKu? J
error('zernpol:Rvector','R must be a vector.') Q9,H0r-%
end k#mQLv
)I7~<$w
r = r(:); 0>@D{_}s
length_r = length(r); /5cFa
q@K8,=/.#
if nargin==4 Ik[aiz
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); ?,GCR1|4
if ~isnorm hP1}Do
error('zernpol:normalization','Unrecognized normalization flag.') ~*:{U
end 7{<:g!
else 1Rrp#E}
isnorm = false; * V;L|c
end g\9I&z~?
'a ]4]d
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %eJolztKZ
% Compute the Zernike Polynomials #rZF4>c
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% U*Q1(C
F3BWi[Xh
% Determine the required powers of r: IQn|0$':Z
% ----------------------------------- h SGI
rpowers = []; VVY#g%(K
for j = 1:length(n) ODS8bD0!i
rpowers = [rpowers m(j):2:n(j)]; vo48\w7[
end &f12Q&jY7
rpowers = unique(rpowers); K@uUe3
,3 !D(&
% Pre-compute the values of r raised to the required powers, \#1*r'V8
% and compile them in a matrix: P .I<.e
% ----------------------------- nR%ASUx:Y
if rpowers(1)==0 e,j2#wjor
rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); fL3Px
rpowern = cat(2,rpowern{:}); CM$q{;y
rpowern = [ones(length_r,1) rpowern]; UO3QwZ4j;
else SePPI.n
rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); j?!BHNs
rpowern = cat(2,rpowern{:}); 8sMDe'
end _<;;CI3w
-e#~CE-
% Compute the values of the polynomials: 9 Vn
% -------------------------------------- )8BGN'jyi
z = zeros(length_r,length_n); %V40I{1
for j = 1:length_n l,z#
:k
s = 0:(n(j)-m(j))/2; )-2sk@y
pows = n(j):-2:m(j); -)cau-(X
for k = length(s):-1:1 FE}!I
p = (1-2*mod(s(k),2))* ... 7d9kr?3(U
prod(2:(n(j)-s(k)))/ ... K})=&<M0
prod(2:s(k))/ ... N0Y$QWr_$
prod(2:((n(j)-m(j))/2-s(k)))/ ... \BIa:}9O
prod(2:((n(j)+m(j))/2-s(k))); a/})X[2
idx = (pows(k)==rpowers); jZRf{
z(:,j) = z(:,j) + p*rpowern(:,idx); ~|W0+ &):
end @UbH;m
YH_mWN\Wu
if isnorm JCL+uEX4S
z(:,j) = z(:,j)*sqrt(2*(n(j)+1)); qG=?+em
end {VBn@^'s
end N)F&c!anh
1|]IWX|
% EOF zernpol