function z = zernpol(n,m,r,nflag) NQqw|3
%ZERNPOL Radial Zernike polynomials of order N and frequency M. 5t:Zp\$+`
% Z = ZERNPOL(N,M,R) returns the radial Zernike polynomials of .{ v$;g
% order N and frequency M, evaluated at R. N is a vector of wlNL;W@w
% positive integers (including 0), and M is a vector with the t/[lA=0 )2
% same number of elements as N. Each element k of M must be a 5&8E{YXr
% positive integer, with possible values M(k) = 0,2,4,...,N(k) %DSr@IX
% for N(k) even, and M(k) = 1,3,5,...,N(k) for N(k) odd. R is }T[@G6#
% a vector of numbers between 0 and 1. The output Z is a matrix |jIH gm
% with one column for every (N,M) pair, and one row for every \9[vi +T
% element in R. 2}&ERW
% Aits<0
% Z = ZERNPOL(N,M,R,'norm') returns the normalized Zernike poly- b d 1^
% nomials. The normalization factor Nnm = sqrt(2*(n+1)) is `%Fp'`ZM$8
% chosen so that the integral of (r * [Znm(r)]^2) from r=0 to <ww D*t
% r=1 is unity. For the non-normalized polynomials, Znm(r=1)=1 ZSu.0|0#
% for all [n,m]. ;VLDXvGd
% yx8G9SO?
% The radial Zernike polynomials are the radial portion of the #R5\k-I
% Zernike functions, which are an orthogonal basis on the unit Kxr{Nx
% circle. The series representation of the radial Zernike *}vvS^ c0
% polynomials is !` 1h *}
% +,spC`M6h
% (n-m)/2 s*GZOz
% __ wNi%u{T
% m \ s n-2s S#GxKMO%
% Z(r) = /__ (-1) [(n-s)!/(s!((n-m)/2-s)!((n+m)/2-s)!)] * r _ &, A
% n s=0 Iynks,ikA
% k1,k 9BK
% The following table shows the first 12 polynomials. jgE{JK\n4
% Lc~m`=B
% n m Zernike polynomial Normalization kZF]BPh.
% --------------------------------------------- v:SHaUS
% 0 0 1 sqrt(2) ) k/&,J3
% 1 1 r 2 br=e+]C Y)
% 2 0 2*r^2 - 1 sqrt(6) i6paNHi*
% 2 2 r^2 sqrt(6) ]-t)wGr
% 3 1 3*r^3 - 2*r sqrt(8) +jE)kaV%
% 3 3 r^3 sqrt(8) &m--}
% 4 0 6*r^4 - 6*r^2 + 1 sqrt(10) 3}}/,pGSc
% 4 2 4*r^4 - 3*r^2 sqrt(10) j#f/M3
% 4 4 r^4 sqrt(10) )#AYb
% 5 1 10*r^5 - 12*r^3 + 3*r sqrt(12) L9/'zhiZBx
% 5 3 5*r^5 - 4*r^3 sqrt(12) ZJ{DW4#t
% 5 5 r^5 sqrt(12) "22./vWV|i
% --------------------------------------------- <l1/lm<#
% ])?dqgwa
% Example: "5eD
>!
% k$v7@|Aw
% % Display three example Zernike radial polynomials F,_cci`p
% r = 0:0.01:1; DAq
H
% n = [3 2 5]; |Kd6.Mx
% m = [1 2 1]; ai?uJ}
% z = zernpol(n,m,r); Q3>qT84
% figure "dCIg{j
% plot(r,z) 4AhFE@
% grid on $MasYi
% legend('Z_3^1(r)','Z_2^2(r)','Z_5^1(r)','Location','NorthWest') q<\r}1Dm
% @Xoh@:j\
% See also ZERNFUN, ZERNFUN2. .U(6])%;@
-v9 (43
% A note on the algorithm. >> cW0I/`
% ------------------------ xLIyh7$t
% The radial Zernike polynomials are computed using the series eQQVfEvS
% representation shown in the Help section above. For many special Oi?Q^ISxP
% functions, direct evaluation using the series representation can <@`K^g;W
% produce poor numerical results (floating point errors), because I&|8
qx#
% the summation often involves computing small differences between u&p8S#e
% large successive terms in the series. (In such cases, the functions =3,<(F5Y[
% are often evaluated using alternative methods such as recurrence _$*-?*V&
% relations: see the Legendre functions, for example). For the Zernike jEKa9rt
% polynomials, however, this problem does not arise, because the 07^.Z[(pCt
% polynomials are evaluated over the finite domain r = (0,1), and T\wOGaCW
% because the coefficients for a given polynomial are generally all _x5-!gK
% of similar magnitude. B#."cg4VR
% (a!E3y5,
% ZERNPOL has been written using a vectorized implementation: multiple F@/syX;bb5
% Zernike polynomials can be computed (i.e., multiple sets of [N,M] 8;=?F>]xn
% values can be passed as inputs) for a vector of points R. To achieve &h[)nD
% this vectorization most efficiently, the algorithm in ZERNPOL Ew}GPJ
% involves pre-determining all the powers p of R that are required to |QzJHP @
% compute the outputs, and then compiling the {R^p} into a single aJm5`az)
% matrix. This avoids any redundant computation of the R^p, and sUF5Yq:9
% minimizes the sizes of certain intermediate variables. _BG`!3U+
% _6FDuCVD-
% Paul Fricker 11/13/2006 dY?l
oFz
&\?{%xj
jM*wm~4>@
% Check and prepare the inputs: Ct/6<
% ----------------------------- @W+8z#xr'
if ( ~any(size(n)==1) ) || ( ~any(size(m)==1) ) ^?%ThPo_
error('zernpol:NMvectors','N and M must be vectors.') JKmd'ZGw
end "~C\Z} ;
a[^dK-
if length(n)~=length(m) ?{Xp'D\z
error('zernpol:NMlength','N and M must be the same length.') unL1/JY z
end \i~5H]?d
9LQy0Gx
n = n(:); gKU*@`6G
m = m(:); g 'L$m|
length_n = length(n); #tPy0QH
'iYaA-9j
if any(mod(n-m,2)) K6<1&
error('zernpol:NMmultiplesof2','All N and M must differ by multiples of 2 (including 0).') r'}#usB(
end b(ryk./ogx
[-[|4|CnOm
if any(m<0) `).;W
error('zernpol:Mpositive','All M must be positive.') $AFiPH9
end (K"t</]
'9wD+'c=A
if any(m>n) qfY=!|O
error('zernpol:MlessthanN','Each M must be less than or equal to its corresponding N.') _ )^n[_E
end Qe/=(P<
;+qPV7Z
if any( r>1 | r<0 ) Dc>)j s|"
error('zernpol:Rlessthan1','All R must be between 0 and 1.') I(WND/&
end A%M&{S'+|X
qpc2;3*7
if ~any(size(r)==1) P3XP=G`E
error('zernpol:Rvector','R must be a vector.') ~w%Z Bp
end Q^V`%+
y+iuA@WCv
r = r(:); **YNR:#Y
length_r = length(r); w1A&p
K[TMTn
if nargin==4
aEZn6k1
isnorm = ischar(nflag) & strcmpi(nflag,'norm'); e;}5~dSi
if ~isnorm d0Kg,HB
error('zernpol:normalization','Unrecognized normalization flag.') zT+yZA.L
end Zr2QeLQC(
else zck |jhJ6
isnorm = false; W%Zyt:H`
end <