The algorithm which shifted the shot gathers in the previous paragraph computes the roots of a simple quadratic expression while looping over the samples of the input shot gather and the geophone locations of the output shot gather. For each sample at time t1 and offset h1 in the original gather s1, a1, b1 are computed according to equations (2) and (3). To construct the shot gather s2 the algorithm loops over the offset h2 computing t2 by solving the quadratic polynomial (10). Since our implementation shct.rst of this algorithm allows different layout parameter for the input and output shot gather, the shot continuation qualifies as a binning operator.