t = 0:0.05:25;
x = exp(-0.05*t).*cos(t);
y = exp(-0.05*t).*sin(t);
z = t;
plot3(x,y,z), grid

b=1200*pi;
dt=50e-6;
for j=1:15
for i=1:150
k(j)=j;
a=(16-j)*50;
t(i)=(i-1)*dt;
y(j,i)=exp(-a*t(i)).*sin(b*t(i));
end
end
>> [K,T]=meshgrid(k,t);
>> mesh(T,K,y)