PETSc bitarrays, efficient storage of arrays of boolean values


typedef char *PetscBT;


The following routines do not have their own manual pages

     PetscBTCreate(m,&bt)         - creates a bit array with enough room to hold m values
     PetscBTDestroy(&bt)          - destroys the bit array
     PetscBTMemzero(m,bt)         - zeros the entire bit array (sets all values to false)
     PetscBTSet(bt,index)         - sets a particular entry as true
     PetscBTClear(bt,index)       - sets a particular entry as false
     PetscBTLookup(bt,index)      - returns the value
     PetscBTLookupSet(bt,index)   - returns the value and then sets it true
     PetscBTLookupClear(bt,index) - returns the value and then sets it false
     PetscBTLength(m)             - returns number of bytes in array with m bits
     PetscBTView(m,bt,viewer)     - prints all the entries in a bit array

PETSc does not check error flags on PetscBTLookup(), PetcBTLookupSet(), PetscBTLength() because error checking would cost hundreds more cycles then the operation.





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