code: public static int cusparseXcsrgemmNnz(
          cusparseHandle handle, 
          int transA, 
          int transB, 
          int m, 
          int n, 
          int k, 
          cusparseMatDescr descrA, 
          int nnzA, 
          Pointer csrSortedRowPtrA, 
          Pointer csrSortedColIndA, 
          cusparseMatDescr descrB, 
          int nnzB, 
          Pointer csrSortedRowPtrB, 
          Pointer csrSortedColIndB, 
          cusparseMatDescr descrC, 
          Pointer csrSortedRowPtrC, 
          Pointer nnzTotalDevHostPtr)
      {
          return checkResult(cusparseXcsrgemmNnzNative(handle, transA, transB, m, n, k, descrA, nnzA, csrSortedRowPtrA, csrSortedColIndA, descrB, nnzB, csrSortedRowPtrB, csrSortedColIndB, descrC, csrSortedRowPtrC, nnzTotalDevHostPtr));
      }
docs: Description: Compute sparse - sparse matrix multiplication for matrices
  stored in CSR format.