OpenCL in R example

opencl-test.R

# OpenCL in R example
#
# Kernel "gpu.sum" sums two vectors.
#
# Please note that in R OpenCL library:
#
#   1. the first argument must be the output vector
#   2. the second argument must be the length of the output
#   3. you must convert the input vectors to the right type ("as.double" here)
#
# (see ?oclRun)

library(OpenCL)
p = oclPlatforms()
d = oclDevices(p[[1]])

code <- c("
   #pragma OPENCL EXTENSION cl_khr_fp64 : enable
   __kernel void gpu_sum(
     // first two args are mandatory
     __global double* output,
     const unsigned int n,
     // user args
     __global const double* input1,
     __global const double* input2
   )
   {
      int i = get_global_id(0);      
      if (i<n) output[i] = input1[i] + input2[i];
   };
")

k.gpu.sum <- oclSimpleKernel(d[[1]], "gpu_sum", code, "double")
vector1 <- as.double(1:10)
vector2 <- as.double(2:11)
result <- oclRun(k.gpu.sum, length(vector1), vector1, vector2)
print(result)

# Output:
#
# > source('opencl-test.R')
#   [1]  3  5  7  9 11 13 15 17 19 21