Argus function = x . (1 - (x/m)^2))^p . exp(-c.(1-(x/m)^2), where m, p, c are some parameters . If we plot this function, we get a long tail (linear) and then a quadratic one. I want to invert this shape. ie: quadratic part appear first and then the linear part. I can do that by inverting the function. But how to do it?