please help i keep getting erro

function sol=samsonwork
global Br Sc delta P K R n epsilon
%x=linspace(-1,1,11);
r=0:0.01:3;
Br=1;Sc=0.4;n=3;delta=0;R=0.5;epsilon=0.1;P=0.3;K=0.3;
solinit=bvpinit(r,[0,0,0,0,0,0]);
sol=bvp4c(@samsonfun,@samsonbc,solinit);
% plot(ans.x(1,:),ans.y(1,:))
end

function f=samsonfun(~,y)
% -Df*y(8)
global Br Sc delta P K R n epsilon g
g = y(3)/ (1+epsilon*y(3));
f=[y(2)
   -P
   y(4)
   R*y(4)-Br*(y(2))^2+delta*(1+epsilon*y(3))* exp g
   y(6)
   Sc*K*(1+epsilon*y(3))^n *exp g];
end

function res=samsonbc(ya,yb)
%global s lambda alpha
res=[ya(1)
    yb(1)-1
    ya(3)
    yb(3)
    ya(5)-1
    yb(5)];
end

[Torsten]

What is

R*y(4)-Br*(y(2))^2+delta*(1+epsilon*y(3))* exp g

Sc*K*(1+epsilon*y(3))^n *exp g];

?

[Torsten]

@Samson comment moved here.

That's my second order equations

[Torsten]

What I mean is:

"exp g" is not a valid MATLAB expression - it will throw an error.

So which mathematical object should "exp g " represent ?

Do you mean exp(g) ? In this case, your code works (see below).

Answer 1

[Torsten]

samsonwork()

ans = struct with fields:
    solver: 'bvp4c'
         x: [0 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600 0.0700 0.0800 0.0900 0.1000 0.1100 0.1200 0.1300 0.1400 0.1500 0.1600 0.1700 0.1800 0.1900 0.2000 0.2100 0.2200 0.2300 0.2400 0.2500 0.2600 0.2700 0.2800 0.2900 0.3000 0.3100 0.3200 0.3300 … ]
         y: [6×301 double]
        yp: [6×301 double]
     stats: [1×1 struct]

function sol=samsonwork
global Br Sc delta P K R n epsilon
%x=linspace(-1,1,11);
r=0:0.01:3;
Br=1;Sc=0.4;n=3;delta=0;R=0.5;epsilon=0.1;P=0.3;K=0.3;
solinit=bvpinit(r,[0,0,0,0,0,0]);
sol=bvp4c(@samsonfun,@samsonbc,solinit);
plot(sol.x,[sol.y(1,:);sol.y(2,:)])
% plot(ans.x(1,:),ans.y(1,:))
end

function f=samsonfun(~,y)
% -Df*y(8)
global Br Sc delta P K R n epsilon g
g = y(3)/ (1+epsilon*y(3));
f=[y(2)
   -P
   y(4)
   R*y(4)-Br*(y(2))^2+delta*(1+epsilon*y(3))* exp(g)
   y(6)
   Sc*K*(1+epsilon*y(3))^n *exp(g)];
end

function res=samsonbc(ya,yb)
%global s lambda alpha
res=[ya(1)
    yb(1)-1
    ya(3)
    yb(3)
    ya(5)-1
    yb(5)];
end

[Samson]

wow