Ground rules for spatial operations algorithm development (cont’d)
GR 6: Use mathematical formulations consistent with GR1:
- use low order piecewise continuous representations when possible
(popularly called table look up). This exploits low cost DRAM,
- do not use in-line table look up for square root or transcendental
functions. It is virtually impossible to compete with built in system
- do use global approximations or piecewise approximation if there is
no high performance system routine. Note that, for example, sin(x) is
not sin(f(x)). Depending on f(x), sin(f(x)) may be better handled by
- if forced to use a series, use only as many terms as required near the
expansion point and more further away from the expansion point,
- for iterative methods determine the number of iterations required
via error analysis and do not use expensive termination tests.