Plotting some piecewise functions in gnuplot

Question

Could you please tell me how can I plot functions that looks like:

f(x)=(x-1)^2 for 0 < x < 1 
f(x)=(x-8)^2 for 1<=x<=7
f(x)=x for x>7

in gnuplot. (If you could tell how to call such a kind of function in English I try to change the topic to the more appropiate).

Answer 1

You can do it in that way:

f(x)=x<=1 ? -(x-1)**2+1 :  x>7 ? (-48)*sin(240)+1+0.5*x : (-(x-1)**2+1)*sin(30*x)+1
plot f(x)