how to change the coefficient of system of ODE with respect to time ?

i recently found a matlab code in https://in.mathworks.com/. i have enclosed that code in this section. in this code, i want to change the coefficient value (transm and recov) with respect to time as given in excel file . Is it possible to change this code with respect to time ?

% Just some start parameters and coefficients
Istart  = 0.01;
Sstart  = 0.99;
Rstart  = 0;
transm  = 3.2;
recov   = 0.23;
maxT    = 20;

% define S',I',R'
% S' = - transm * S * I
% I' = transm * S I - recov * I
% R' = recov * I
% S is y(1)
% I is y(2)
% R is y(3)
%so here fun = @(t,y)[S'; I'; R'];
fun     = @(t,y)[-transm*y(1)*y(2); (transm*y(1)*y(2))-(recov*y(2)); recov*y(2)];

% Provide the starting parameters
Y0      = [Sstart; Istart; Rstart;];

% Define the range of t
tspan   = [0 maxT];

% Magic happens and matrix Y contains S,I,R
[T,Y]   = ode45(fun,tspan,Y0);

% Plot plot
figure
plot(T,abs(Y(:,1)),'b-') % S
hold on
plot(T,abs(Y(:,2)),'r-') % I
plot(T,abs(Y(:,3)),'g-') % R

Answer 1

[Star Strider]

Interpolate from the Excel file, and choose a stiff solver:

% Just some start parameters and coefficients
Istart  = 0.01;
Sstart  = 0.99;
Rstart  = 0;
maxT    = 20;

T1 = readtable('data.xls');

interptransm = @(t) interp1(T1.t, T1.transm, t, 'linear','extrap');     % Interpolate
interprecov = @(t) interp1(T1.t, T1.recov, t, 'linear','extrap');       % Interpolate

%so here fun = @(t,y)[S'; I'; R'];
fun     = @(t,y)[-interptransm(t)*y(1)*y(2); (interptransm(t)*y(1)*y(2))-(interprecov(t)*y(2)); interprecov(t)*y(2)];

% Provide the starting parameters
Y0      = [Sstart; Istart; Rstart;];

% Define the range of t
tspan   = [0 maxT];

% Magic happens and matrix Y contains S,I,R
[T,Y]   = ode15s(fun,tspan,Y0);

% Plot plot
figure
semilogy(T,abs(Y(:,1)),'b-') % S
hold on
plot(T,abs(Y(:,2)),'r-') % I
plot(T,abs(Y(:,3)),'g-') % R
hold off
grid
legend('S', 'I', 'R', 'Location', 'N')

producing:

.

[Deva Narayanan]

@ Star Strider; Thank u so much

[Star Strider]

As always, my pleasure!