eigen multithreading c++11

I have a code to compute a Gaussian Mixture Model with Expectation Maximization in order to identify the clusters from a given input data sample.

A piece of the code is repeating the computation of such model for a number of trials Ntrials (one indepenendet of the other but using the same input data) in order to finally pick up the best solution (the one maximizing the total likelihood from the model). This concept can be generalized to many other clustering algorithms (e.g. k-means).

I want to parallelize the part of the code that has to be repeated Ntrials times through multi-threading with C++11 such that each thread will execute one trial.

A code example, assuming an input Eigen::ArrayXXd sample of (Ndimensions x Npoints) can be of the type:

    double bestTotalModelProbability = 0;
    Eigen::ArrayXd clusterIndicesFromSample(Npoints);
    clusterIndicesFromSample.setZero();

    for (int i=0; i < Ntrials; i++)
    {
         totalModelProbability = computeGaussianMixtureModel(sample);


         // Check if this trial is better than the previous one.
         // If so, update the results (cluster index for each point
         // in the sample) and keep them.

         if totalModelProbability > bestTotalModelProbability
         {
             bestTotalModelProbability = totalModelProbability;
             ...
             clusterIndicesFromSample = obtainClusterMembership(sample);
         }
    }

where I pass the reference value of sample (Eigen::Ref), and not sample itself to both the functions computeGaussianMixtureModel() and obtainClusterMembership().

My code is heavily based on Eigen array, and the N-dimensional problems that I take can account for order 10-100 dimensions and 500-1000 different sample points. I am looking for some examples to create a multi-threaded version of this code using Eigen arrays and std:thread of C++11, but could not find anything around and I am struggling with making even some simple examples for manipulation of Eigen arrays.

I am not even sure Eigen can be used within std::thread in C++11. Can someone help me even with some simple example to understand the synthax? I am using clang++ as compiler in Mac OSX on a CPU with 6 cores (12 threads).