Blackman window with the exact coefficients {7938 9240 1430}/18608 on [-1/2 1/2]
ExactBlackmanWindow[x]
Plot[ExactBlackmanWindow[x], {x, -1, 1}]
→ -Graphics-Plot3D[ExactBlackmanWindow[x]ExactBlackmanWindow[y], {x, -1, 1}, {y, -1, 1}, PlotRange -> All]
→ -Graphics3D-ExactBlackmanWindow[0.1]
→ 0.8520642374237258