# Heat transfer differential equation

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Enrico Danzi on 10 Dec 2019
Answered: Enrico Danzi on 10 Dec 2019
Dear all,
I'm quite a new user of Matlab, I'm asking you somethiing that could be simple or obvious, but I've tried and no reasonable results came uot.
I've to calculate the Temperature evolution in time of a system affected by heat conduction and radiation, this is my equation:
and this is my attempt code:
function[yp] = f(t,y);
% defining constants
d = 0.00585;
l = 0.03325;
m = 0.009329;
v = 20;
cp = 0.5;
nu = 16.24*10^-6;
sigma = 5.6704*10^-6;
eps = 0.8;
h = (0.26*((d/nu)*v)^0.6)*(0.7^0.37);
A = 7.926*10^-4;
k1 = (h*A)/(m*cp);
k2 = (sigma*eps*A)/(m*cp);
ya = 299;
% equation
yp = k1*(y-ya)+k2*(y^4);
Then, on the command window:
[t,y] = ode45('f',[0,5],1673)
What I am doing wrong (in the problem formulation, I don't care for instance to numbers)?
Thanks for any help!

darova on 10 Dec 2019
Call the function this way:
[t,y] = ode45(@f,[0,5],1673)

Enrico Danzi on 10 Dec 2019
I've solved my question using ode113:
[t,y] = ode113(@(t,y) -k1*(y-299)-k2*y^4,[0 100],1673)
, which eventually worked better and did not have any integration step tolerance warnings.