Next: About
this document Up: Conjugate
Direction Minimization: An Previous: References
Figure 1
This graph shows the drop in the value of the function that is minimized
in refinement over 20 cycles of refinement. Four different methods of minimization
are compared. In some test runs (solid lines) only the positional parameters
were varied while in the rest (broken lines) both the positional and thermal
parameters were varied. The function is
after the
's and
's have been scaled to each other, plus the sum of the geometry deviation
terms. The methods represented with triangles required 18.5 minutes of
CPU time per cycle on a VAX 3600 computer. The methods represented with
squares required the additional calculation of curvatures and took 22 minutes
per cycle.
This plot demonstrates that the conjugate direction method produces
a lower function value for a given number of cycles of refinement.
Dale Edwin Tronrud
Thu Nov 20 10:28:11 PST 1997