It seems that the Dense(M, N, min, max) constructor is not completely random.

[lotz84]

Running the following simple program

#include <iostream>
#include <monolish_blas.hpp>

int main() {
  monolish::matrix::Dense<double>x(2, 3, 0.0, 10.0);
  x.print_all();
  return 0;
}

$ g++ -O3 main.cpp -o main.out -lmonolish_cpu

will produce results like this.

root@636020fa2fd8:/$ ./main.out
1 1 5.27196
1 2 2.82358 <--
1 3 2.13893 <--
2 1 9.72054
2 2 2.82358 <--
2 3 2.13893 <--
root@636020fa2fd8:/$ ./main.out
1 1 5.3061
1 2 9.75236
1 3 7.15652
2 1 5.28961
2 2 2.05967
2 3 0.59838
root@636020fa2fd8:/$ ./main.out
1 1 9.33149 <--
1 2 4.75639 <--
1 3 8.71093 <--
2 1 9.33149 <--
2 2 4.75639 <--
2 3 8.71093 <--

The arrows (<--) indicate that the number is repeating.

This is probably due to that the pseudo-random number generator does not split well when it is parallelized by OpenMP.

monolish/src/utils/dense_constructor.cpp

Lines 120 to 127 in 1b89942

	std::random_device random;
	std::mt19937 mt(random());
	std::uniform_real_distribution<> rand(min, max);
	#pragma omp parallel for
	for (size_t i = 0; i < val.size(); i++) {
	val[i] = rand(mt);
	}

This may happen not only with Dense, but also with random constructors of other data structures.

I tested this on docker image ghcr.io/ricosjp/monolish/mkl:0.14.1.

[t-hishinuma]

Thanks for reporting the bug.
You're probably right. I also think it's a problem with OpenMP parallelization.

I'll check and fix it next week.

[t-hishinuma]

This is due to the fact that random_device is declared thread-local.
This bug occurs in the following two functions:

• Dense Constructor
  https://github.com/ricosjp/monolish/blob/master/src/utils/dense_constructor.cpp#L111
• Vector Constructor https://github.com/ricosjp/monolish/blob/master/src/utils/vector_constructor.cpp#L44

On the other hand, the random_vector function in include/common/monolish_common.hpp is not parallelized.

I will parallelize all functions, declaring the random_vector variable as a local variable of the thread.

[t-hishinuma]

I used the following test program to test it. This is not included in test/.

#include<monolish_blas.hpp>

int main(){
    monolish::vector<double> x(100000, 0.1, 1.0);
    x.print_all();

    return 0;
}

./a.out | uniq | wc

[t-hishinuma]

I have fixed the bug with the following commit.
3ccf1d6

Thanks for your reports!

[lotz84]

Quick and appropriate fix! Thank you.