# respected sir, if i am using syms function to calculate the value of differential equation,in result i am getting a fractional value where num and den are very large.so can you tell me how to represent these fraction in small digits.

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ABHILASH SINGH on 26 Sep 2016
Answered: Walter Roberson on 26 Sep 2016
clc;
clear all;
syms z;
lamda= input ('enter the vehicle arrival rate =');
r= input ('enter the transmission range=');
l= input ('enter the avg. road length=');
% k=lamda/l;
e=2.72;
lamda_1=lamda*r
rho=lamda_1*(e^(-lamda_1))
rho_1=e^(-lamda_1)
%%%%%%%when lambda*r>=ln(4)
a1(z)=sqrt(1-(4*rho_1*z^2))
h_1(z)=(a1(z))*((1-rho_1*rho)*z^3-(1-rho_1)*z^2-(1-rho)*z+2-rho-rho_1);
h_2(z)=e^((.5*lamda_1)*((a1(z)))-1)*(2*rho*z^3+2*rho_1*z^2-z-1+(z-1)*((a1(z))));
h_3(z)=((rho_1+rho-1)*z^3)+((1-3*rho_1-2*rho)*z^2)+((1-rho)*z)+rho_1+rho;
m_1(z)=(h_1(z)+h_2(z)+h_3(z))/((rho*(z^2))*(1+(a1(z)))-(2*z*exp((0.5*lamda_1)*(((a1(z)))-1))));
a(z)=abs(diff(m_1(z),z));
z=1;
e_noofhops(z)=abs(rho_1+2*rho+2*rho*m_1(1)+rho*a(1))
e_size=(1/(lamda*e^(-lamda*r)))-(1/lamda) %size in terms of length%
e_noofhops_l(z)=(e_noofhops(z)*l)/(e_size)
%%%%total_d(delay) is calculated by multiplying E(no. of hops)_L by the delay taken by a vehicle to transmit its message(t_h)
% t_h=input('enter the delay taken by a vehicle to transmit its message=');
% total_d=e_noofhops_l(z)*t_h;

Walter Roberson on 26 Sep 2016
If you want to see, for example, 3 digits for e_noofhops_l, then you could use
vpa(e_noofhops_l, 3)
or you could use
format short
double(e_noofhops_l)
(which would show 5 digits)