Determinant and permanent: Difference between revisions
→{{header|Common Lisp}}
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return 0;
}</lang>
=={{header|C++}}==
{{trans|Java}}
<lang cpp>#include <iostream>
#include <vector>
template <typename T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &v) {
auto it = v.cbegin();
auto end = v.cend();
os << '[';
if (it != end) {
os << *it;
it = std::next(it);
}
while (it != end) {
os << ", " << *it;
it = std::next(it);
}
return os << ']';
}
using Matrix = std::vector<std::vector<double>>;
Matrix squareMatrix(size_t n) {
Matrix m;
for (size_t i = 0; i < n; i++) {
std::vector<double> inner;
for (size_t j = 0; j < n; j++) {
inner.push_back(nan(""));
}
m.push_back(inner);
}
return m;
}
Matrix minor(const Matrix &a, int x, int y) {
auto length = a.size() - 1;
auto result = squareMatrix(length);
for (int i = 0; i < length; i++) {
for (int j = 0; j < length; j++) {
if (i < x && j < y) {
result[i][j] = a[i][j];
} else if (i >= x && j < y) {
result[i][j] = a[i + 1][j];
} else if (i < x && j >= y) {
result[i][j] = a[i][j + 1];
} else {
result[i][j] = a[i + 1][j + 1];
}
}
}
return result;
}
double det(const Matrix &a) {
if (a.size() == 1) {
return a[0][0];
}
int sign = 1;
double sum = 0;
for (size_t i = 0; i < a.size(); i++) {
sum += sign * a[0][i] * det(minor(a, 0, i));
sign *= -1;
}
return sum;
}
double perm(const Matrix &a) {
if (a.size() == 1) {
return a[0][0];
}
double sum = 0;
for (size_t i = 0; i < a.size(); i++) {
sum += a[0][i] * perm(minor(a, 0, i));
}
return sum;
}
void test(const Matrix &m) {
auto p = perm(m);
auto d = det(m);
std::cout << m << '\n';
std::cout << "Permanent: " << p << ", determinant: " << d << "\n\n";
}
int main() {
test({ {1, 2}, {3, 4} });
test({ {1, 2, 3, 4}, {4, 5, 6, 7}, {7, 8, 9, 10}, {10, 11, 12, 13} });
test({ {0, 1, 2, 3, 4}, {5, 6, 7, 8, 9}, {10, 11, 12, 13, 14}, {15, 16, 17, 18, 19}, {20, 21, 22, 23, 24} });
return 0;
}</lang>
{{out}}
<pre>[[1, 2], [3, 4]]
Permanent: 10, determinant: -2
[[1, 2, 3, 4], [4, 5, 6, 7], [7, 8, 9, 10], [10, 11, 12, 13]]
Permanent: 29556, determinant: 0
[[0, 1, 2, 3, 4], [5, 6, 7, 8, 9], [10, 11, 12, 13, 14], [15, 16, 17, 18, 19], [20, 21, 22, 23, 24]]
Permanent: 6.7788e+06, determinant: 0</pre>
=={{header|Common Lisp}}==
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