function mat6(q,ra,rb,rc,r,er1,er2,choice);

%function coax(q,ra,rb,rc,r,er1,er2,choice);
%This routine is accompanied by the graphic H1P26.GIF

%sv is the solution vector

e0=8.85e-12;

% NOTE e==E in region 1, f==E in region 2

f1='e=q/(2*pi*e0*er1*r)';
f2='f=q/(2*pi*e0*er2*r)';
f3='v=q*(log(rb/rc)/er2+log(rc/ra)/er1)/(2*pi*e0)';
f4='c=q/v';

sv=solve(f1,f2,f3,f4,'e,f,v,c');

if choice==1
mat20(eval(sv.e),'V/m')
end

if choice==2
mat20(eval(sv.f),'V/m')
end

if choice==3
mat20(eval(sv.v),'V')
end

if choice==4
mat20(eval(sv.c),'F')
end
