Guide to programming using RSF

Fortran 90 program

• Declare input, output and auxiliary file tags.

• Declare RSF cube axes: at time axis, ax space axis, az depth axis.

• Declare multi-dimensional arrays for input, output and computations.

• Open files for input/output.

• Read axes from input files; write axes to output file.

• Allocate arrays and read wavelet, velocity and reflectivity.

• Allocate temporary arrays.

• Loop over time.

• Compute Laplacian: $\Delta U$.

• Inject source wavelet: $\left[ \Delta U - f(t) \right]$

• Scale by velocity: $\left[ \Delta U - f(t) \right] v^2$

• Time step: $U_{i+1} = \left[ \Delta U -f(t) \right] v^2 \Delta t^2 + 2 U_{i} - U_{i-1}$