INTRODUCTION

In geophysical mapping and imaging applications we set up linear equations of high order. We face subjective issues like how to scale components of an operator and how much damping (regularization) to use. Here I summarize a few scaling tricks. Please keep in mind that we do not have matrices (data structures) but operators, i.e., function pairs for applying an operator $\bold F$ and its adjoint (transpose). In other words, nifty methods and theories for matrices are often not applicable.