From help-request at octave dot org Tue Jan 11 05:24:03 2005
Subject: Re: ODE system solving
From: "homer_jay at katamail dot com" <homer_jay@katamail.com>
To: help at octave dot org
Date: Tue, 11 Jan 2005 11:25:44 +0000

i've tryed to write an m-file containing all the instructions for solving my equations. this is the file:

# dovrebbe calcolare la T(z) e w(z) per una bava di GR, processo Neumag
y0=[57 0.186 520];
z=linspace(0,1000,2000)';
y=lsode(SysO,y0,z);
plot(z,y(:,3)-273)
# inizio della descrizione del sistema
function SysO=f(y,z)
g=9810;  				# mm2/s
rho=7.65e-07;				# kg/mm3
Cp=1500;				# J/Kg k
Ka=3e-5;				# W/mm k
R1=0.53;				# mm
w0=57;					# mm/s
Va=1000;				# mm/s
Ta=25+273;				# k
Etap=0.434*exp(508.3/y(3));		# Pa/s
Nup=Etap/rho;				# mm2/s
dNup=-Etap*508.3/(y(3)^2*rho);		
a=0.41;
b=0.61;
Nua=10.2+0.131*(y(3)-273);		# mm2/s
Rz=R1*sqrt(w0/y(1));			# mm
Re=2*y(1)*Rz/Nua;
Cd=a*Re^b;
tau=(1/2)*Cd*rho*y(1)^2;
hc=0.21*Re^(1/3)*Ka/Rz*(1+(8*Va/Rz))^(1/6);
SysO(1)=y(2); 
SysO(2)=y(1)*y(2)/(3*Nup)-(g/(3*Nup))+(2*tau/(3*Nup*rho*Rz))+((y(2)^2)/y(1))-(1/Nup)*dNup*y(2)*(-2*hc*(y(3)-Ta)/(Rz*rho*Cp*y(1)));
SysO(3)=-2*hc*(y(3)-Ta)/(Rz*rho*Cp*y(1));
endfunction


it doesn't work!!! octave crush!!!
what can i do? 


2nd question? how can i solve a boundary value problem for my equations?

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