please help i keep getting erro

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Samson
Samson 2023-3-8
评论： Samson 2023-3-13
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
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Torsten
Torsten 2023-3-10
@Samson comment moved here.
That's my second order equations
Torsten
Torsten 2023-3-10
编辑：Torsten 2023-3-10
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).

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Torsten
Torsten 2023-3-10
Ran in:
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

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