; To plot this, press Esc, then press P twice
1 / (9 + x^2 + y^2)
; A mountain and a crater
- y / (9 + x^2 + y^2)
; Two mountains
1 / (9 + x^2 + (y - 3)^2) + 1 / (9 + x^2 + (y + 3)^2)
; A hanging valley
7 * x^2 - y^3
; A saddle
y^2 - x^2
; A sway-back roof
y^2 / 5 - 3 * ABS x
; A pinched ridge
(y^2 + 1/10) / (x^2 + y^2 + 1/10)
; A monkey saddle
y * (3 * x^2 - y^2)
; A pinched monkey saddle
x*y * (SIGN (x + 1/10) * SQRT (x^2 + y^2) + 2*y) / (x^2 + y^2 + 1/10)
; Intersecting ridges
- SQRT ABS (x*y)
; A pagoda roof
- SQRT ABS x - SQRT ABS y
; A ridge intersecting a valley
SQRT ABS x - SQRT ABS y
; A ridge that becomes a valley
- y * SQRT ABS x
; A volcano
50 / (50 + ((x^2 + y^2)^(1/2) - 37/10)^2) - 1
; A sombrero
COS ((x^2 + y^2) / 4) / (3 + x^2 + y^2)
; A surfer's perfect wave
EXP (- x/9) * (pi / 2 - ATAN y)
; A cliff is born
ATAN (- y, x + 1/10)
; Two mountains separated by a crater
- COS (3 * PI * X/10) * COS (PI * Y /10)
; Three mountains
- COS (3 * PI * X/10) * SIN (PI * Y/5)
