f(0)=f(0+0)=f(0)+f(0)
f(0)=0
f(3)=f(2+1)=f(2)+f(1)=f(1+1)+f(1)=3f(1)
f(1)=f(0.5+0.5)=2f(0.5)
f(0.5)=0.5f(1)
f(0)=f((-x)+f(x))=f(-x)+f(x)=0
f(-x)=-f(x)
f(-x)f(x)=-(f(-x))^2
f(0)=f(0+0)=f(0)+f(0)
f(0)=0
f(3)=f(2+1)=f(2)+f(1)=f(1+1)+f(1)=3f(1)
f(1)=f(0.5+0.5)=2f(0.5)
f(0.5)=0.5f(1)
f(0)=f((-x)+f(x))=f(-x)+f(x)=0
f(-x)=-f(x)
f(-x)f(x)=-(f(-x))^2