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| === Creating shape manipulation functions === See [[MorphoOptimizationProject_Manipulating_MRIS_et_al]] |
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| ==== mris_fix_topology has a hot loop, which does unnecessary calculations of the face normals ==== mrisComputeOptimalRetessellation and mrisComputeRandomRetessellation have a similar structure _:_: it loops over a set of patches, or iterates on one patch. For each patch it calls _:_:_: mrisDefectPatchFitness, which calls _:_:_:_: mrisComputeDefectLogLikelihood, which calls _:_:_:_:_: mrisComputeDefectMRILogUnlikelihood, which _:_:_:_:_:_: does an expensive computation all the face normals for ALL the faces _:_:_:_:_:_: does two other expensive steps, which only use a few of the face normals ==== To simplify, the original code does this ==== _: loop _:_: for all fno normal[fno] = f (inputs) _:_: for a few fno use normal[fno] _: end loop _: change some inputs _: use some normal[fno] ''Since only a few of the face normals are used, it is a waste of time to calculate all of them every time around the loop! '' ==== This is replaced by code that does ==== _: loop _:_: for all fno: normal[fno].deferred = true _:_: for a few fno: use normal[fno], computing it from f (inputs) if is deferred, and changing it to being no-longer deferred _: end loop _: compute any remaining deferred normal[fno] before their inputs can change _: change some inputs _: use some normal[fno] ==== How can we test it gets the right answers? ==== When checking code is enabled, the normal[fno] is computed from the inputs twice - once when it is deferred, and again when it is undeferred. It is checked that these two values are the same. ==== How do we make sure that the undeferring is done? ==== If we left the __FACE nx,ny,nz,orig_area__ members unchanged, then it would be hard to find all the users. We could just rename them, but it is easier to place them in a struct and have a function called to get a pointer to the struct, and have the function do the undeferral. This is a standard data hiding technique, implemented here in C. Now all the places that need to be changed are compilation errors. '''Why put the structs into a separate vector?''' TBD |
See [[MorphoOptimizationProject_Deferring_calculations]] |
Parent: MorphoOptimizationProject
A variety of techniques have been used.
Creating shape manipulation functions
See MorphoOptimizationProject_Manipulating_MRIS_et_al