


 Accelerating seismic computations using customized number representations on FPGAs  

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Brief Introduction
The code above is the computationally intensive portion of the FK
step in a downward continuation based migration. The governing equation for the
FK step is the Double Square Root Equation (DSR) (, ). The DSR equation
describes how to downward continue a wavefield one depth step. The
equation is valid for a constant velocity medium and is based on the wave number
of the source and receiver . The DSR equation can be written as,

(3) 
where is frequency. The code takes the approach of building a priori
a relatively small
table
of the possible values of
. The code then performs a table lookup
that converts a given
value to an approximate value of
the square root.
In practical applications wfld contains millions of
elements. The computation pattern of this function makes it an
ideal target to map to a streaming hardware circuit on an FPGA.



 Accelerating seismic computations using customized number representations on FPGAs  

Next: Circuit Design
Up: Case Study I: Complex
Previous: Case Study I: Complex
20070918