These two files are libraries for the rest of system. Users are not encouraged
to modify the library unless users are extremely familiar with the codes 

In sketch.k, two sketch computation strategies are implemented, point-wise 
convolution and dot product based shifting method. Generally the functions
ending with "conv" are for convolution, otherwise they are dot product.

Also unitary or Demitri 's random vectors are used to project data vector, 
which is compared with normal distribution or Indyk 's normal distribution.

Some conventions:
"tr-": transform
"conv": convolution
"indyk": random vectors are drawn from normal distribution.
"new": unitary random vectors

For those intermediate functions, users need not go into the details. They
are no more than programing tricks in K.