Function linspace

test/testingutilities.cpp:606–661

Enumerates all permutations

// Enumerates all permutations
std::vector<std::vector<double>> linspace(std::vector<double> start, std::vector<double> end, std::vector<unsigned int> points)
{
    assert(start.size() == end.size() && end.size() == points.size());

    size_t nDims = start.size();
    size_t numPoints = 1;
    for(size_t i = 0; i < nDims; i++) {
        numPoints *= points.at(i);
    }

#ifndef NDEBUG
    if(numPoints > 10000) {
        std::cout << "Warning: Enumerating " << numPoints << " points." << std::endl;
    }
#endif // ifndef NDEBUG

    auto result = std::vector<std::vector<double>>(numPoints);

    auto dx = std::vector<double>(nDims);
    auto it = std::vector<unsigned int>(nDims);
    auto cur = std::vector<double>(nDims);

    for(unsigned int i = 0; i < nDims; i++) {
        cur.at(i) = start.at(i);
        it.at(i) = 0;
        dx.at(i) = (end.at(i) - start.at(i)) / (points.at(i) - 1);
    }

    size_t curDim = 0;
    size_t i = 0;
    // Add the start vector
    result.at(i++) = std::vector<double>(start);
    while(true) {
        curDim = 0;
        while(curDim < nDims && it.at(curDim)+1 >= points.at(curDim)) {
            it.at(curDim) = 0;
            cur.at(curDim) = start.at(curDim) + dx.at(curDim) * it.at(curDim);
            curDim++;
        }
        // If we're unable to find a number that can be increased,
        // it means were at the highest number
        // (for 4 digits in decimal that is 9999)
        if(curDim >= nDims) {
            break;
        }

        it.at(curDim)++;
        cur.at(curDim) = start.at(curDim) + dx.at(curDim) * it.at(curDim);

        result.at(i++) = std::vector<double>(cur);
    }

    assert(i == numPoints);

    return result;
}

std::vector<std::vector<double>> linspace(int dim, double start, double end, unsigned int points)