Just Google it

1.2+(sqrt(1-(sqrt(x^2+y^2))^2) + 1 - x^2-y^2) * (sin (10000 * (x*3+y/5+7))+1/4) from -1.6 to 1.6


100-3/(sqrt(x^2+y^2))+sin(sqrt(x^2+y^2))+sqrt(200-(x^2+y^2)+10*sin(x)+10sin(y))/1000, x is from -15 to 15, y is from -15 to 15, z is from 90 to 101


5 + (-sqrt(1-x^2-(y-abs(x))^2))*cos(30*((1-x^2-(y-abs(x))^2))), x is from -1 to 1, y is from -1 to 1.5, z is from 1 to 6


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