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rocBLAS Level 1 Dot Example

Description

This example showcases the usage of rocBLAS' Level 1 DOT function. The Level 1 API defines operations between vector and vector. DOT is a dot product operator between $x$ and $y$ vectors defined as $\sum_i{x_i \cdot y_i}$.

Application flow

  1. Read in and parse command line parameters.
  2. Allocate and initialize host vectors.
  3. Compute CPU reference result.
  4. Create a rocBLAS handle.
  5. Allocate and initialize device vectors.
  6. Use the rocBLAS handle to enable passing the h_result parameter via a pointer to host memory.
  7. Call rocblas_sdot() asynchronous rocBLAS dot product function.
  8. Copy the result from device to host.
  9. Destroy the rocBLAS handle, release device memory.
  10. Validate the output by comparing it to the CPU reference result.

Command line interface

The application provides the following optional command line arguments:

  • -x or --incx. The stride between consecutive values in the data array that makes up vector $x$, must be greater than zero. Its default value is 1.
  • -y or --incy. The stride between consecutive values in the data array that makes up vector $y$, must be greater than zero. Its default value is 1.
  • -n. The number of elements in vectors $x$ and $y$. Its default value is 5.

Key APIs and Concepts

  • rocBLAS is initialized by calling rocblas_create_handle(rocblas_handle*) and it is terminated by calling rocblas_destroy_handle(rocblas_handle).
  • The pointer mode controls whether scalar parameters must be allocated on the host (rocblas_pointer_mode_host) or on the device (rocblas_pointer_mode_device). It is controlled by rocblas_set_pointer_mode.
  • rocblas_Xdot computes the dot product of two vectors as defined above. X is one of s (single-precision: rocblas_float), d (double-precision: rocblas_double), h (half-precision: rocblas_half), c (single-precision complex: rocblas_complex), or z (double-precision complex: rocblas_double_complex).

Demonstrated API Calls

rocBLAS

  • rocblas_create_handle
  • rocblas_destroy_handle
  • rocblas_handle
  • rocblas_float
  • rocblas_int
  • rocblas_set_pointer_mode
  • rocblas_pointer_mode_host
  • rocblas_sdot
  • rocblas_status
  • rocblas_status_success
  • rocblas_status_to_string

HIP runtime

  • hipFree
  • hipMalloc
  • hipMemcpy
  • hipMemcpyDeviceToHost
  • hipMemcpyHostToDevice