This gives the meaning of the terms as generally understood in the middle of the 18th century. Robert Hooper's Physician's Vade-Mecum, published in 1812 has been used as a source of terms in the early 19th century; many of the terms mentioned are still in common use.
In either case, the value at x = 0 is defined to be the limiting value sinc(0) = 1. The normalization causes the definite integral of the function over the real numbers to equal 1 (whereas the same integral of the unnormalized sinc function has a value of Ï).
So since the interval we're looking at is y = sin x, x = -pi/2. . pi/2: At-pi/2, sin x is -1 (since 3pi/2 - 2pi = -pi/2) and at pi/2, sin x = 1. At 0, sin x = 0. So start from (-pi/2, -1), draw the right half of a concave-up curve up to (0,0), then the left half of a concave-down curve up to (pi/2, 1).o since the interval we're looking at is y = sin x, x = -pi/2. . pi/2: At-pi/2, sin x is -1 (since 3pi/2 - 2pi = -pi/2) and at pi/2, sin x = 1. At 0, sin x = 0. So start from (-pi/2, -1), draw the right half of a concave-up curve up to (0,0), then the left half of a concave-down curve up to (pi/2, 1).