Index Exceeds number of array elements (1)

function ydot = fossil_fules(t,y)

p=y(1);os=y(2);od=y(3);as=y(4);ad=y(5);
r= [0.0,0.0,1.0,4.0,5.0,8.0,10.0,10.5,10.0,8.0,3.5,2.0,0.0,0.0];
yr= [1000,1850,1950,1980,2000,2050,2080,2100,2120,2150,2225,2300,2500,5000];
f = pchip(yr,r);

d = 8.65;
m1 =4.95*10^2;
m2 =4.95*10^-2;
vs =0.12;
vd =1.23;
w =10^-3;
k1 =2.19*10^-4;
k2 =6.12*10^-5;
k3 =0.997148;
k4 =6.79*10^-2;

hs = (os-(os^2 - k3*as*(2*os-as))^0.5) / k3;
cs = (as-hs)/2;
ps = k4*((hs^2)/cs);

ydot = [(ps-p/d)+f(t)/m1 ; 1/vs*((od-os)*w-k1-(ps-p/d)*m2) ; 1/vd *(k1-(od-os)*w) ; 1/vs *((ad-as)*w-k2) ; 1/vd *(k2-(ad-as)*w)];


end

Error is in line 3 "p=y(1);os=y(2);od=y(3);as=y(4);ad=y(5);"

Answer 1

[Star Strider]

I suspect your initial conditions vector in your ode solver call only has one element. It should be a 5-element vector.

You would have to post that so we could see it.

[Matthew Windoloski]

tspan = [1000,5000];  
yzero = [1.00;2.01;2.23;2.20;2.26];  

[t,y] = ode45(@fossil_fules,tspan,yzero)

This is the ode solver im using

[Star Strider]

I get a different error:

Index exceeds the number of array elements (1).

Error in fossil_fules (line 19)
ydot = [(ps-p/d)+f(t)/m1 ; 1/vs*((od-os)*w-k1-(ps-p/d)*m2) ; 1/vd *(k1-(od-os)*w) ; 1/vs
*((ad-as)*w-k2) ; 1/vd *(k2-(ad-as)*w)];

The probleml seems to be that ‘f’ is (1x1) and ‘t’ is 1000.

I suspect that you’re using pchip incorrectly.

If I create an anonymous function with your pchip call:

f = @(tq) pchip(yr,r,tq);

your code runs without error.

[Matthew Windoloski]

It works! thank you so much

[Star Strider]

As always, my pleasure!