function z = zernpol(n,m,r,nflag) 2.]~*7
%ZERNPOL Radial Zernike polynomials of order N and frequency M. ^ b@!dS
% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of PDhWFF
% order N and frequency M, evaluated at R. N is a vector of ja?s@Y}-9s
% positive integers (including 0), and M is a vector with the {-Yee[d<?
% same number of elements as N. Each element k of M must be a 3Mw}R6g@#
% positive integer, with possible values M(k) = 0,2,4,...,N(k) Q2q|*EL
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is ^ZR8s^X
% a vector of numbers between 0 and 1. The output Z is a matrix )R~a;?T_c0
% with one column for every (N,M) pair, and one row for every A$Wx#r7)
% element in R. W;.{]x.0
% goB;EWz
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- Gp,'kw"I
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is o,J^ e_
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to # J]~
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 n_J5zQJ
% for all [n,m]. n%*tMr9 s
% h<)yJh
% The radial Zernike polynomials are the radial portion of the w?_`/oqd|
% Zernike functions, which are an orthogonal basis on the unit nW11wtiO.
% circle. The series representation of the radial Zernike }Fm\+JOS
% polynomials is 2qlIy
% "ct58Y@
% (n-m)/2 (V!0'9c
% __ aV#h5s
% m \ s n-2s !O 8.#+
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r fQO
""qh
% n s=0 u3ST;
% |*ReqM|_C
% The following table shows the first 12 polynomials. K_Re}\D
% B2Z0
% n m Zernike polynomial Normalization }1Z6e[K?
% --------------------------------------------- 5/,Qz>QE[
% 0 0 1 sqrt(2) d+e0;!s~O
% 1 1 r 2 83Uw
% 2 0 2*r^2 - 1 sqrt(6) `6}Yqh))
% 2 2 r^2 sqrt(6) _Z$?^gn
% 3 1 3*r^3 - 2*r sqrt(8) S2Vx e@b)
% 3 3 r^3 sqrt(8) ']h
IfOD"r
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) >8(jW
% 4 2 4*r^4 - 3*r^2 sqrt(10) J)KnE2dw5
% 4 4 r^4 sqrt(10) T0Q51Q
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) CbQ4Y
% 5 3 5*r^5 - 4*r^3 sqrt(12) 8jNOEM(0Y+
% 5 5 r^5 sqrt(12) #2N_/J(U
% --------------------------------------------- +KP_yUq[
% _JA:.V^3gm
% Example: :X Lp
% TL@mM
% % Display three example Zernike radial polynomials 5NFRPGYX
% r = 0:0.01:1; c 6q/X*
% n = [3 2 5]; "&<~UiI
% m = [1 2 1]; Why"G1`
% z = zernpol(n,m,r); M $uf:+F
% figure d- kZt@DL=
% plot(r,z) .
pP7"E4]
% grid on 32^#RlSu8
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') 4 4`WYK l
% 2vvh|?M
% See also ZERNFUN, ZERNFUN2. In+^V([u+_
w5(yCyNp~
% A note on the algorithm. `M0YAiG
% ------------------------ ;W6-i2?
% The radial Zernike polynomials are computed using the series 7 Kjj?~RA
% representation shown in the Help section above. For many special nALnB1
% functions, direct evaluation using the series representation can Gnv!]c&S>l
% produce poor numerical results (floating point errors), because y@aKNWy}$
% the summation often involves computing small differences between 3a^)u-9,x
% large successive terms in the series. (In such cases, the functions kC31$jMC3!
% are often evaluated using alternative methods such as recurrence 3Y(9\}E@`
% relations: see the Legendre functions, for example). For the Zernike M}KZG'7
% polynomials, however, this problem does not arise, because the =hhvmo
% polynomials are evaluated over the finite domain r = (0,1), and 2`E!| X
% because the coefficients for a given polynomial are generally all gb(#DbI
% of similar magnitude. 9t0Cj/w}
% K( z[}
% ZERNPOL has been written using a vectorized implementation: multiple wonYm27f
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] %ZiK[e3G
% values can be passed as inputs) for a vector of points R. To achieve cd+^=esSO
% this vectorization most efficiently, the algorithm in ZERNPOL .jaZ|nN8`
% involves pre-determining all the powers p of R that are required to 4&]%e6,jH
% compute the outputs, and then compiling the {R^p} into a single lz}llLb1
% matrix. This avoids any redundant computation of the R^p, and (V)9s\Le_
% minimizes the sizes of certain intermediate variables. +dM.-wW
% .aJ%am/:%
% Paul Fricker 11/13/2006 zsQF,7/}B
7JS#a=D#
NA\ x<
% Check and prepare the inputs: "vsjen.K>
% ----------------------------- s.KOBNCFa
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) zu<>"5}]
error('zernpol:NMvectors','N and M must be vectors.') [WYJrk.
end ~ur)fAuF2
\QiqcD9Y
if length(n)~=length(m) C[g&F0 6
error('zernpol:NMlength','N and M must be the same length.') Cc*|Zw
end >pnz_MQ
.jCk#@+
n = n(:); "~Us#4>
m = m(:); N4s$.`
length_n = length(n); kHZKj!!R
E tdd\^
if any(mod(n-m,2)) oR7 7`
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') x7Eeb!s0f,
end (KZUvsS k
S~}$Ly@
if any(m<0) 6mX: =Q
error('zernpol:Mpositive','All M must be positive.') IK85D>00T
end R+C+$?4NG
aL{EkiR
if any(m>n) ]D?oQ$q7
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') WtMcI>4w
end 3$;J0{&[i
!P+~c0DF
if any( r>1 | r<0 ) P~;<o!f
error('zernpol:Rlessthan1','All R must be between 0 and 1.') >Y44{D\`
end WReYF+Uen
`;R|V
if ~any(size(r)==1) I):m6y@
error('zernpol:Rvector','R must be a vector.') zaQ$ Ht
end *vEU}SxRuv
X+fuhcn
r = r(:); ':9%3Wq]j
length_r = length(r); PpI+@:p[
jqV)V> M.
if nargin==4 Q3'(f9
x
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); "'Q$.sR
if ~isnorm ;2+FgOj
error('zernpol:normalization','Unrecognized normalization flag.') ot&j HS'
end ?Yynd
else U0lqGEZ
isnorm = false; &6=TtTp"9
end h Kp,4D>2_
%`t]FV^#
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% S}XB
|
% Compute the Zernike Polynomials Qr^Z~$i t
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% f=-!2#%
8Iqk%n~(
% Determine the required powers of r: ==r?
% ----------------------------------- _ d(Ks9
rpowers = []; 'Kt4O9=p
for j = 1:length(n) s~IA},F,\
rpowers = [rpowers m(j):2:n(j)]; VdjU2d
end J%O[@jX1
rpowers = unique(rpowers); J"a2
@S&
pU'`9fLi_
% Pre-compute the values of r raised to the required powers, <*b]JY V@
% and compile them in a matrix: _mI:Lr#dT
% ----------------------------- pE YrmC
if rpowers(1)==0 ,i$(yx?
rpowern = arrayfun(@(p)r.^p,rpowers(2:end),'UniformOutput',false); 4IGQ,RTB
rpowern = cat(2,rpowern{:}); A+bubH,
rpowern = [ones(length_r,1) rpowern]; 0YsN82IDD
else 4p/V6kr&r
rpowern = arrayfun(@(p)r.^p,rpowers,'UniformOutput',false); @zVBn~=i
rpowern = cat(2,rpowern{:}); 6{FS/+
end p1`'1`.3
* zJiii
% Compute the values of the polynomials: G3^n_]Jb
% -------------------------------------- ;MdK3c
z = zeros(length_r,length_n); 9O0
for j = 1:length_n Z:o'
+oh
s = 0:(n(j)-m(j))/2; CH R?i1e
pows = n(j):-2:m(j); m= beB\=
for k = length(s):-1:1 EF7|%N
p = (1-2*mod(s(k),2))* ... yrvSbqR
prod(2:(n(j)-s(k)))/ ... Aaw:B?4)
prod(2:s(k))/ ... uzn))/"
prod(2:((n(j)-m(j))/2-s(k)))/ ... BX)cV
prod(2:((n(j)+m(j))/2-s(k))); 1wH/ #K
idx = (pows(k)==rpowers); (L6]uNOG
z(:,j) = z(:,j) + p*rpowern(:,idx); OmUw.VH
end 9[]"%6
T;pn -
if isnorm MsiC!j.-
z(:,j) = z(:,j)*sqrt(2*(n(j)+1)); |(8Hk@\CT>
end 1X:whS5S
end L5N{ie_
+H^V},dBp!
% EOF zernpol