sinc function
t=sinc(x)
:x real or complex vector or matrix : :t real or complex vector or matrix :
If x is a vector or a matrix, t=sinc(x) is the vector or matrix such that t(i)=sin(x(i))/x(i) if x(i)~=0 and t(i)=1 if x(i)==0.
x=`linspace`_(-10,10,3000);
`plot2d`_(x,sinc(x))