feat(equation-and-linear-solve): step 2 — pardiso-linear-solver

include/fesa/solvers/linear/linear_solver.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <span>
+#include <vector>
+
+#include <fesa/assembly/symmetric_csr.hpp>
+#include <fesa/core/diagnostic.hpp>
+
+namespace fesa {
+
+struct LinearSolveResult final {
+    std::vector<double> solution;
+    double relative_residual{};
+    std::vector<Diagnostic> diagnostics;
+};
+
+class LinearSolver {
+public:
+    virtual ~LinearSolver() = default;
+
+    [[nodiscard]] virtual LinearSolveResult solve(
+        const SymmetricCsr& matrix,
+        std::span<const double> rhs) = 0;
+};
+
+}  // namespace fesa