# Error using FDE12

조회 수: 24(최근 30일)
Kesavan K 2022년 5월 13일
댓글: nazish yamin 2022년 5월 17일
I am trying to solve a SERID mathematical model with matlab.
This involves the freactional derivatives. In order to solve these equation I tried to run the code using fde12.
But, there are errors and I dont know what to do.
Any support or help is appreciated.
function [time,state_values]= mathematical1
%%Initial values
t0 = 0;
tend = 100;
%tspan=[t0,tend];
y0 = [100,10,3,0,0];
%%Constant(rates) values
A=0; % Migrated Population into the considered community
e=0.3; % Contact rate between S and E
a=0.4; % Contact rate between S and I
g=0.23; % Recovery rate
k=0.3; % Rate of Exposed to Infected
p=0.25; % Exposed to Recovery
m=0.12; % Death rate from Infected
b=0.45; % Recovery rate recovered from disease and alive
%% [sdot] = g(t,s)
sdot = @(t,s)[A-(e*s(1)*s(2))-(a*s(1)*s(3))+(g*s(4));
-((k+p)*s(2))+(e*s(1)*s(2))+(a*s(1)*s(3));......
-((b+m)*s(3))+(k*s(2));
-(g*s(4))+(p*s(2))+(b*s(3));
(m*s(3))];
h = 2^(-6);
alpha= 0.8;
[time, state_values] = fde12(alpha, sdot, t0,tend,y0,h);
%%Extracting individual values
S= state_values(:,1);
E= state_values(:,2);
I= state_values(:,3);
R= state_values(:,4);
D= state_values(:,5);
%%Plot S,E,I,R,D
figure(1)
clf
plot(time,S); title('Susceptible Population vs Time')
figure(2)
clf
plot(time,E); title('Exposed Population vs Time')
figure(3)
clf
plot(time,I); title('Infected Population vs Time')
figure(4)
clf
plot(time,R); title('Recovered Population vs Time')
figure(5)
clf
plot(time,D); title('Death Population vs Time')
end
ERRORS:
##### 댓글 수: 2표시숨기기 이전 댓글 수: 1
Kesavan K 2022년 5월 13일
function [t, y] = fde12(alpha,fdefun,t0,tfinal,y0,h,param,mu,mu_tol)
%FDE12 Solves an initial value problem for a non-linear differential
% equation of fractional order (FDE). The code implements the
% predictor-corrector PECE method of Adams-Bashforth-Moulton type
% described in [1].
%
% [T,Y] = FDE12(ALPHA,FDEFUN,T0,TFINAL,Y0,h) integrates the initial value
% problem for the FDE, or the system of FDEs, of order ALPHA > 0
% D^ALPHA Y(t) = FDEFUN(T,Y(T))
% Y^(k)(T0) = Y0(:,k+1), k=0,...,m-1
% where m is the smallest integer grater than ALPHA and D^ALPHA is the
% fractional derivative according to the Caputo's definition. FDEFUN is a
% function handle corresponding to the vector field of the FDE and for a
% scalar T and a vector Y, FDEFUN(T,Y) must return a column vector. The
% set of initial conditions Y0 is a matrix with a number of rows equal to
% the size of the problem (hence equal to the number of rows of the
% output of FDEFUN) and a number of columns depending on ALPHA and given
% by m. The step-size H>0 is assumed constant throughout the integration.
%
% [T,Y] = FDE12(ALPHA,FDEFUN,T0,TFINAL,Y0,H,PARAM) solves as above with
% the additional set of parameters for the FDEFUN as FDEFUN(T,Y,PARAM).
%
% [T,Y] = FDE12(ALPHA,FDEFUN,T0,TFINAL,Y0,H,PARAM,MU) solves the FDE with
% the selected number MU of multiple corrector iterations. The following
% values for MU are admissible:
% MU = 0 : the corrector is not evaluated and the solution is provided
% just by the predictor method (the first order rectangular rule);
% MU > 0 : the corrector is evaluated by the selected number MU of times;
% the classical PECE method is obtained for MU=1;
% MU = Inf : the corrector is evaluated for a certain number of times
% until convergence of the iterations is reached (for convergence the
% difference between two consecutive iterates is tested).
% The defalut value for MU is 1
%
% [T,Y] = FDE12(ALPHA,FDEFUN,T0,TFINAL,Y0,H,PARAM,MU,MU_TOL) allows to
% specify the tolerance for testing convergence when MU = Inf. If not
% specified, the default value MU_TOL = 1.E-6 is used.
%
% FDE12 is an implementation of the predictor-corrector method of
% Adams-Bashforth-Moulton studied in [1]. Convergence and accuracy of
% the method are studied in [2]. The implementation with multiple
% corrector iterations has been proposed and discussed for multiterm FDEs
% in [3]. In this implementation the discrete convolutions are evaluated
% by means of the FFT algorithm described in [4] allowing to keep the
% computational cost proportional to N*log(N)^2 instead of N^2 as in the
% classical implementation; N is the number of time-point in which the
% solution is evaluated, i.e. N = (TFINAL-T)/H. The stability properties
% of the method implemented by FDE12 have been studied in [5].
%
% [1] K. Diethelm, A.D. Freed, The Frac PECE subroutine for the numerical
% solution of differential equations of fractional order, in: S. Heinzel,
% T. Plesser (Eds.), Forschung und Wissenschaftliches Rechnen 1998,
% Gessellschaft fur Wissenschaftliche Datenverarbeitung, Gottingen, 1999,
% pp. 57-71.
%
% [2] K. Diethelm, N.J. Ford, A.D. Freed, Detailed error analysis for a
% fractional Adams method, Numer. Algorithms 36 (1) (2004) 31-52.
%
% [3] K. Diethelm, Efficient solution of multi-term fractional
% differential equations using P(EC)mE methods, Computing 71 (2003), pp.
% 305-319.
%
% [4] E. Hairer, C. Lubich, M. Schlichte, Fast numerical solution of
% nonlinear Volterra convolution equations, SIAM J. Sci. Statist. Comput.
% 6 (3) (1985) 532-541.
%
% [5] R. Garrappa, On linear stability of predictor-corrector algorithms
% for fractional differential equations, Internat. J. Comput. Math. 87
% (10) (2010) 2281-2290.
%
% Copyright (c) 2011-2012, Roberto Garrappa, University of Bari, Italy
% garrappa at dm dot uniba dot it
% Revision: 1.2 - Date: July, 6 2012
% Check inputs
if nargin < 9
mu_tol = 1.0e-6 ;
if nargin < 8
mu = 1 ;
if nargin < 7
param = [] ;
end
end
end
% Check order of the FDE
if alpha <= 0
error('MATLAB:fde12:NegativeOrder',...
['The order ALPHA of the FDE must be positive. The value ' ...
'ALPHA = %f can not be accepted. See FDE12.'], alpha);
end
% Check the step--size of the method
if h <= 0
error('MATLAB:fde12:NegativeStepSize',...
['The step-size H for the method must be positive. The value ' ...
'H = %e can not be accepted. See FDE12.'], h);
end
% Structure for storing initial conditions
ic.t0 = t0 ;
ic.y0 = y0 ;
ic.m_alpha = ceil(alpha) ;
ic.m_alpha_factorial = factorial(0:ic.m_alpha-1) ;
% Structure for storing information on the problem
Probl.ic = ic ;
Probl.fdefun = fdefun ;
Probl.problem_size = size(y0,1) ;
Probl.param = param ;
% Check number of initial conditions
if size(y0,2) < ic.m_alpha
error('MATLAB:fde12:NotEnoughInputs', ...
['A not sufficient number of assigned initial conditions. ' ...
'Order ALPHA = %f requires %d initial conditions. See FDE12.'], ...
alpha,ic.m_alpha);
end
% Check compatibility size of the problem with size of the vector field
f_temp = f_vectorfield(t0,y0(:,1),Probl) ;
if Probl.problem_size ~= size(f_temp,1)
error('MATLAB:fde12:SizeNotCompatible', ...
['Size %d of the problem as obtained from initial conditions ' ...
'(i.e. the number of rows of Y0) not compatible with the ' ...
'size %d of the output of the vector field FDEFUN. ' ...
'See FDE12.'], Probl.problem_size,size(f_temp,1));
end
% Number of points in which to evaluate weights and solution
r = 16 ;
N = ceil((tfinal-t0)/h) ;
Nr = ceil((N+1)/r)*r ;
Q = ceil(log2(Nr/r)) - 1 ;
NNr = 2^(Q+1)*r ;
% Preallocation of some variables
y = zeros(Probl.problem_size,N+1) ;
fy = zeros(Probl.problem_size,N+1) ;
zn_pred = zeros(Probl.problem_size,NNr+1) ;
if mu > 0
zn_corr = zeros(Probl.problem_size,NNr+1) ;
else
zn_corr = 0 ;
end
% Evaluation of coefficients of the PECE method
nvett = 0 : NNr+1 ;
nalpha = nvett.^alpha ;
nalpha1 = nalpha.*nvett ;
PC.bn = nalpha(2:end) - nalpha(1:end-1) ;
PC.an = [ 1 , (nalpha1(1:end-2) - 2*nalpha1(2:end-1) + nalpha1(3:end)) ] ;
PC.a0 = [ 0 , nalpha1(1:end-2)-nalpha(2:end-1).*(nvett(2:end-1)-alpha-1)] ;
PC.halpha1 = h^alpha/gamma(alpha+1) ;
PC.halpha2 = h^alpha/gamma(alpha+2) ;
PC.mu = mu ; PC.mu_tol = mu_tol ;
% Initializing solution and proces of computation
t = t0 + (0 : N)*h ;
y(:,1) = y0(:,1) ;
fy(:,1) = f_temp ;
[y, fy] = Triangolo(1, r-1, t, y, fy, zn_pred, zn_corr, N, PC, Probl ) ;
% Main process of computation by means of the FFT algorithm
ff = [0 2 ] ; nx0 = 0 ; ny0 = 0 ;
for q = 0 : Q
L = 2^q ;
[y, fy] = DisegnaBlocchi(L, ff, r, Nr, nx0+L*r, ny0, t, y, fy, ...
zn_pred, zn_corr, N, PC, Probl ) ;
ff = [ff ff] ; ff(end) = 4*L ;
end
% Evaluation solution in TFINAL when TFINAL is not in the mesh
if tfinal < t(N+1)
c = (tfinal - t(N))/h ;
t(N+1) = tfinal ;
y(:,N+1) = (1-c)*y(:,N) + c*y(:,N+1) ;
end
t = t(1:N+1) ; y = y(:,1:N+1) ;
end
% =========================================================================
% =========================================================================
% r : dimension of the basic square or triangle
% L : factor of resizing of the squares
function [y, fy] = DisegnaBlocchi(L, ff, r, Nr, nx0, ny0, t, y, fy, ...
zn_pred, zn_corr, N , PC, Probl)
nxi = nx0 ; nxf = nx0 + L*r - 1 ;
nyi = ny0 ; nyf = ny0 + L*r - 1 ;
is = 1 ;
s_nxi(is) = nxi ; s_nxf(is) = nxf ; s_nyi(is) = nyi ; s_nyf(is) = nyf ;
i_triangolo = 0 ; stop = 0 ;
while ~stop
stop = nxi+r-1 == nx0+L*r-1 | (nxi+r-1>=Nr-1) ; % Ci si ferma quando il triangolo attuale finisce alla fine del quadrato
[zn_pred, zn_corr] = Quadrato(nxi, nxf, nyi, nyf, fy, zn_pred, zn_corr, PC, Probl) ;
[y, fy] = Triangolo(nxi, nxi+r-1, t, y, fy, zn_pred, zn_corr, N, PC, Probl) ;
i_triangolo = i_triangolo + 1 ;
if ~stop
if nxi+r-1 == nxf % Il triangolo finisce dove finisce il quadrato -> si scende di livello
i_Delta = ff(i_triangolo) ;
Delta = i_Delta*r ;
nxi = s_nxf(is)+1 ; nxf = s_nxf(is) + Delta ;
nyi = s_nxf(is) - Delta +1; nyf = s_nxf(is) ;
s_nxi(is) = nxi ; s_nxf(is) = nxf ; s_nyi(is) = nyi ; s_nyf(is) = nyf ;
else % Il triangolo finisce prima del quadrato -> si fa un quadrato accanto
nxi = nxi + r ; nxf = nxi + r - 1 ; nyi = nyf + 1 ; nyf = nyf + r ;
is = is + 1 ;
s_nxi(is) = nxi ; s_nxf(is) = nxf ; s_nyi(is) = nyi ; s_nyf(is) = nyf ;
end
end
end
end
% =========================================================================
% =========================================================================
function [zn_pred, zn_corr] = Quadrato(nxi, nxf, nyi, nyf, fy, zn_pred, zn_corr, PC, Probl)
coef_beg = nxi-nyf ; coef_end = nxf-nyi+1 ;
funz_beg = nyi+1 ; funz_end = nyf+1 ;
% Evaluation convolution segment for the predictor
vett_coef = PC.bn(coef_beg:coef_end) ;
vett_funz = [fy(:,funz_beg:funz_end) , zeros(Probl.problem_size,funz_end-funz_beg+1) ] ;
zzn_pred = real(FastConv(vett_coef,vett_funz)) ;
zn_pred(:,nxi+1:nxf+1) = zn_pred(:,nxi+1:nxf+1) + zzn_pred(:,nxf-nyf+1-1:end-1) ;
% Evaluation convolution segment for the corrector
if PC.mu > 0
vett_coef = PC.an(coef_beg:coef_end) ;
if nyi == 0 % Evaluation of the lowest square
vett_funz = [zeros(Probl.problem_size,1) , fy(:,funz_beg+1:funz_end) , zeros(Probl.problem_size,funz_end-funz_beg+1) ] ;
else % Evaluation of any square but not the lowest
vett_funz = [ fy(:,funz_beg:funz_end) , zeros(Probl.problem_size,funz_end-funz_beg+1) ] ;
end
zzn_corr = real(FastConv(vett_coef,vett_funz)) ;
zn_corr(:,nxi+1:nxf+1) = zn_corr(:,nxi+1:nxf+1) + zzn_corr(:,nxf-nyf+1:end) ;
else
zn_corr = 0 ;
end
end
% =========================================================================
% =========================================================================
function [y, fy] = Triangolo(nxi, nxf, t, y, fy, zn_pred, zn_corr, N, PC, Probl)
for n = nxi : min(N,nxf)
% Evaluation of the predictor
Phi = zeros(Probl.problem_size,1) ;
if nxi == 1 % Case of the first triangle
j_beg = 0 ;
else % Case of any triangle but not the first
j_beg = nxi ;
end
for j = j_beg : n-1
Phi = Phi + PC.bn(n-j)*fy(:,j+1) ;
end
St = StartingTerm(t(n+1),Probl.ic) ;
y_pred = St + PC.halpha1*(zn_pred(:,n+1) + Phi) ;
f_pred = f_vectorfield(t(n+1),y_pred,Probl) ;
if PC.mu == 0
y(:,n+1) = y_pred ;
fy(:,n+1) = f_pred ;
else
j_beg = nxi ;
Phi = zeros(Probl.problem_size,1) ;
for j = j_beg : n-1
Phi = Phi + PC.an(n-j+1)*fy(:,j+1) ;
end
Phi_n = St + PC.halpha2*(PC.a0(n+1)*fy(:,1) + zn_corr(:,n+1) + Phi) ;
yn0 = y_pred ; fn0 = f_pred ;
stop = 0 ; mu_it = 0 ;
while ~stop
yn1 = Phi_n + PC.halpha2*fn0 ;
mu_it = mu_it + 1 ;
if PC.mu == Inf
stop = norm(yn1-yn0,inf) < PC.mu_tol ;
if mu_it > 100 && ~stop
warning('MATLAB:fde12:NonConvegence',...
strcat('It has been requested to run corrector iterations until convergence but ', ...
'the process does not converge to the tolerance %e in 100 iteration'),PC.mu_tol) ;
stop = 1 ;
end
else
stop = mu_it == PC.mu ;
end
fn1 = f_vectorfield(t(n+1),yn1,Probl) ;
yn0 = yn1 ; fn0 = fn1 ;
end
y(:,n+1) = yn1 ;
fy(:,n+1) = fn1 ;
end
end
end
% =========================================================================
% =========================================================================
function z = FastConv(x, y)
r = length(x) ; problem_size = size(y,1) ;
z = zeros(problem_size,r) ;
X = fft(x,r) ;
for i = 1 : problem_size
Y = fft(y(i,:),r) ;
Z = X.*Y ;
z(i,:) = ifft(Z,r) ;
end
end
% =========================================================================
% =========================================================================
function f = f_vectorfield(t,y,Probl)
if isempty(Probl.param)
f = feval(Probl.fdefun,t,y) ;
else
f = feval(Probl.fdefun,t,y,Probl.param) ;
end
end
% =========================================================================
% =========================================================================
function ys = StartingTerm(t,ic)
ys = zeros(size(ic.y0,1),1) ;
for k = 1 : ic.m_alpha
ys = ys + (t-ic.t0)^(k-1)/ic.m_alpha_factorial(k)*ic.y0(:,k) ;
end
end

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### 답변(1개)

VBBV 2022년 5월 13일
편집: VBBV 2022년 5월 13일
s = 1:4; % define s vector passed as argument to function line below e.g. values
sdot = @(t,s)[A-(e*s(1)*s(2))-(a*s(1)*s(3))+(g*s(4));
-((k+p)*s(2))+(e*s(1)*s(2))+(a*s(1)*s(3));......
-((b+m)*s(3))+(k*s(2));
-(g*s(4))+(p*s(2))+(b*s(3));
(m*s(3))];
[time, state_values] = fde12(alpha, sdot, t0,tend,y0,h); % function
Define the s vector before passing anonymous function sdot as argument to fde12
##### 댓글 수: 3표시숨기기 이전 댓글 수: 2
nazish yamin 2022년 5월 17일
I think y_0 should be a column vector.

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R2021b

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