# potenza in sinusoidale

f0 = 12   # V
R  = 50   # Ohm 
nu =1000  # Hz
om = 2*pi*nu
T = 1/nu

tofile = TRUE
f.name = "potenza_sinusoidale_C.png"
if(tofile) png(file=f.name, width = 960, height = 480,
               units = "px", pointsize = 12)
old.mar = par("mar")
par(mar=c(3.9,4.0,0.1,0.1))   # margini ottimizzati

curve(cos(om*x*T), -0.5, 1.5, xlab='t / T',
      ylab='f(t)/f0;  P(t)/Pmax', lwd=3, col='blue')
abline(h=0)
grid()
curve(cos(om*x*T+pi/2), lwd=3, col='green', add=TRUE)
curve(-sin(2*om*x*T), lwd=3, col='red', n=201, add=TRUE)
abline(h=0, lty=2, col=2)

par(mar=old.mar)
if(tofile) dev.off()