I have implemented my own version of algorithm to multiply two matrices together and I need someone who know what they are doing to see if there is anything that can be done in a more optimal way. I am also keen on understanding how I can make it robust such that it doesn't crash when non-rectangular matrices are passed as argument i.e. matrix that has uneven number of elements in different Vds it holds.
I am particularly interested in function matrixDot in the code bellow, everything else is only to show how I am using it in my project).
#include "iostream"
#include <vector>
#define LOG(m) std::cout << m << std::endl
struct Vd
{
std::vector<double> v;
};
struct Md
{
std::vector<Vd> m;
//fill matrix with num
void fill(unsigned const int rows, unsigned const int cols, const double num)
{
m.clear();
for (unsigned int i = 0; i < rows; i++)
{
Vd tempVec;
for (unsigned int j = 0; j < cols; j++)
{
tempVec.v.push_back(num);
}
m.push_back(tempVec);
}
}
friend std::ostream& operator << (std::ostream& out, const Md& mat)
{
out << "[" << std::endl << std::endl;
for (unsigned int i = 0; i < mat.m.size(); i++)
{
out << "[";
for (unsigned int j = 0; j < mat.m[i].v.size(); j++)
{
if (j % mat.m[i].v.size() == mat.m[i].v.size() - 1)
out << mat.m[i].v[j] << "]" << std::endl << std::endl;
else
out << mat.m[i].v[j] << ", ";
}
}
out << "]" << std::endl;
return out;
}
};
inline void matrixDot(const Md& m1, const Md& m2, Md& outm)
{
if (m1.m[0].v.size() && m2.m.size())
if (m1.m[0].v.size() != m2.m.size())
{
LOG("Shape mismatch: " << "matrix1 columns: " << m1.m[0].v.size() << ", " << "matrix2 rows: " << m2.m.size());
throw std::exception();
}
unsigned int m1x = 0; unsigned int m1y = 0; unsigned int m2y = 0; //m2y = m1x
while (outm.m.size() < m1.m.size())
{
Vd tempv;
while (tempv.v.size() < m2.m[0].v.size())
{
double total = 0.0;
while (m1x < m1.m[0].v.size())
{
total += m1.m[m1y].v[m1x] * m2.m[m1x].v[m2y];
m1x++;
}
tempv.v.push_back(total);
m1x = 0;
m2y < m2.m[0].v.size() - 1 ? m2y++ : m2y = 0;
}
m1y < m1.m.size() - 1 ? m1y++ : m1y = 0;
outm.m.push_back(tempv);
}
}
int main()
{
Md mat1;
mat1.fill(5, 2, 1.0);
Md mat2;
mat2.fill(2, 6, 2.0);
Md mat3;
matrixDot(mat1, mat2, mat3);
std::cout << mat3;
}
