(1, 3) +
The plus sign keeps both diagonals as mirrors. A cross through the centre, with arcs closing off the corners.
- Plate
- Square, free edges
- Mode numbers
- m = 1, n = 3, plus combination
- Shape
- cos(1πx/a)cos(3πy/a) + cos(3πx/a)cos(1πy/a)
- Wavenumber k·a
- 9.93 (a = 240 mm)
- Frequency
- 422 Hz on the reference plate