Hands-On GPU Programming with Python and CUDA

Level-2 GEMV in cuBLAS

Let's look at how to do a GEMV matrix-vector multiplication. This is defined as the following operation for an m x n matrix A, an n-dimensional vector x, a m-dimensional vector y, and for the scalars alpha and beta:

Now let's look at how the function is laid out before we continue:

cublasSgemv(handle, trans, m, n, alpha, A, lda, x, incx, beta, y, incy)  

Let's go through these inputs one-by-one:

• handle refers to the cuBLAS context handle.
• trans refers to the structure of the matrix—we can specify whether we want to use the original matrix, a direct transpose, or a conjugate transpose (for complex matrices). This ...