# PetscBT

PETSc bitarrays

### Synopsis

    typedef char* PetscBT;

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 PetscBTLength(m) - returns number of bytes in array with m bits PetscBTView(m,bt,viewer) - prints all the entries in a bit array

The are all implemented as macros with the trivial data structure for efficiency.

These are not thread safe since they use a few global variables.

We do not currently check error flags on PetscBTSet(), PetscBTClear(), PetscBTLookup(), PetcBTLookupSet(), PetscBTLength() cause error checking would cost hundreds more cycles then the operation.

Level:advanced
Location:include/petscbt.h
Index of all Sys routines
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Index of all manual pages