Create test and correct some mistakes

src/test_suite.cpp

@@ -1,9 +1,35 @@
+#include <cassert>
+#include <cmath>
 
+#include "matrix.hpp"
 
-void test_tridiag_setup() {
+void test_create_symmetric_tridiagonal() {
+    double tol = 10e-8;
+    double diff;
+    int N = 6;
+    double h = 1./(double) (N+1);
+    double a = -1. / (h*h), d = 2. / (h*h);
 
+    arma::mat A = create_symmetric_tridiagonal(N, a, d);
+
+    arma::vec eigval;
+    arma::mat eigvec;
+
+    arma::eig_sym(eigval, eigvec, A);
+
+    for (int i=0; i < N; i++) {
+        diff = eigval(i) - (d + 2.*a*std::cos(((i+1.)*M_PI)/(N+1.)));
+        assert(std::abs(diff) < tol); 
+    }
 }
 
 void test_max_off_diag_symmetric() {
 
 }
+
+int main() {
+
+    test_create_symmetric_tridiagonal();
+
+    return 0;
+}