Fsolve error with vertcat

Hello, I have tried to run this code but I get a vertcat error. The goal is to solve a system of 2 non linear vectorial equations by using fsolve and finding 'vi' and 'a'.

%% Data
R=5.5;
n=1000;
drdr=1/n;
drdr=0.1:drdr:1;
dr=R/n;
r=R*drdr;
c=0.3;
rho=1.225;
theta_0=0.2618; %collective pitch [rad]
theta_twist=0.0349; %[rad]
theta_r=theta_0 + r.*theta_twist; %[rad]
b=4; 
V_tip=205;
Omega=V_tip/R; % [rad/s]
Vc=5;
%% Swirl
phi_swirl=@(vi,a) atan((vi + Vc)./((1-a).*Omega.*r));
U=@(vi,a) sqrt(((1-a).*Omega.*r).^2 + (vi + Vc).^2);
alpha_swirl=@(vi,a) theta_r - atan((vi + Vc)./((1-a).*Omega.*r));
G_swirl=@(vi,a) 2./pi.*acos(exp(-b./2.*(1-drdr)./(drdr.*(atan((vi+Vc)./(((1-a).*Omega.*r)))))));
F_swirl1=@(vi,a) 0.5.*b.*rho.*U(vi,a).^2.*2.*pi.*alpha_swirl(vi,a).*cos(phi_swirl(vi,a)).*c.*dr ...
    -4.*pi.*rho.*r.*vi.*(vi+Vc).*G_swirl(vi,a).*dr;
F_swirl2= @(vi,a) 0.5.*b.*rho.*U(vi,a).^2.*(2.*pi.*alpha_swirl(vi,a).*sin(phi_swirl(vi,a))+cdr.*cos(phi_swirl(vi,a))).*c.*r.*dr...
    -4.*pi.*Omega.*a.*(vi+Vc).*r.^3.*dr;
F_swirl=@(vi,a) [F_swirl1;F_swirl2];
Initialguess=[zeros(1,numel(drdr));zeros(1,numel(drdr))];
vi_a=fsolve(F_swirl,Initialguess);

The error is the following. Any idea to solve it?

Error using vertcat
Nonscalar arrays of function handles are not allowed; use cell arrays instead.
Error in Untitled2>@(vi,a)[F_swirl1;F_swirl2]
Error in fsolve (line 242)
            fuser = feval(funfcn{3},x,varargin{:});
Error in Untitled2 (line 32)
vi_a=fsolve(F_swirl,Initialguess);
Caused by:
    Failure in initial objective function evaluation. FSOLVE cannot continue.