Originally Posted by

**radioheadfan** I have been trying to figure this out for a couple of hours now. Help please.

Okay here is the mfile I'm using. Titled f

function zi = f(x, y)

q = .6; %transmisiivity of solar glazing

s = 1; %absorptivity of adobe walls

c = 0; %thermal capacitance of the maternity house

d = 4.55; %area of solar collector (m^2)

r = 198.63; %1/Rt

e = 5; %ambient temp.

zi =(((q.*s.*c.*d)-((y-e)/r))./c);

Then we typed into the command window the following string:

>> a = 0;

>> b = 86400;

>> y0 = 20;

>> [x,y]=ode45('f',[a,b],y0)

The values resulted in

x = 0.000000000

0.000000000000

etc

y = NaN

NaN

NaN

etc.

These values are obviously wrong, help please!