Error with ode45 when using a decreasing x value: more non-singleton rhs dimensions than non-singleton subscripts

I am working on a problem in which I use ode45 to estimate an equation as x goes from 8 to .0, using 78 steps of the size .1. Y is increasing as x decreases.

The equation is: function f=fun2(t,y) f=('-(sqrt(100-t^2)/(t))')

I used a linspace to hold the step values: p=linspace(8,0.2,78)

With the initial y value to be 6, I set it all up as:

[x,y]=ode45('fun2',p,6)

However, I am consistently getting this error:

"Assignment has more non-singleton rhs dimensions than non-singleton subscripts

Error in ode45 (line 184) k_(:,1)=feval(FUN,t,x); % first stage"

What am I doing wrong, and how can I fix this? I am quite new to Matlab, and am not sure what to do.

Answer 1

[Torsten]

function main
tspan=linspace(8,0.2,78);
y0=6;
[t,y]=ode45(@fun2,tspan,y0)

function f = fun2(t,y) 
f=-sqrt(100-t^2)/t;
end

Best wishes

Torsten.