be carefull ed. Equation (1.7) applies to a periodic continuous-time signal whose fundamental pe d T has any positive value. Equation (1.10) applies to a periodic discrete-time signa ose fundamental period N can assume only a positive integer value. 1 x(t) 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Time t, seconds 1 FIGURE 1.15 Triangular wave alternating between -1 and +1 for Problem 1.3.