eigen: svd example, use pkg-config

kernel_module/user/Makefile

@@ -15,6 +15,7 @@ endif
 ifeq ($(BR2_PACKAGE_EIGEN),y)
 	# Header only.
 	#LIBS += -leigen
+	CXXFLAGS_EXTRA += $(shell $(PKG_CONFIG) --cflags --libs eigen3)
 else
 	OUTS := $(filter-out eigen%$(OUT_EXT),$(OUTS))
 endif

kernel_module/user/README.adoc

@@ -30,7 +30,3 @@ These programs can also be compiled and used on host.
 .. link:ioctl.c[]
 .. link:netlink.c[]
 .. link:poll.c[]
-. Buildroot libraries
-.. link:eigen.cpp[]
-.. link:openmp.c[]
-.. link:openblas.c[]

kernel_module/user/eigen.cpp

@@ -1,14 +1,11 @@
-/* Official hello world. */
-
+/* Adapted from: https://eigen.tuxfamily.org/dox/GettingStarted.html */
 #include <iostream>
-#include <eigen3/Eigen/Dense>
-using Eigen::MatrixXd;
-int main()
-{
-  MatrixXd m(2,2);
-  m(0,0) = 3;
-  m(1,0) = 2.5;
-  m(0,1) = -1;
-  m(1,1) = m(1,0) + m(0,1);
-  std::cout << m << std::endl;
+#include <Eigen/Dense>
+int main() {
+	Eigen::MatrixXd m(2,2);
+	m(0,0) = 3;
+	m(1,0) = 2.5;
+	m(0,1) = -1;
+	m(1,1) = m(1,0) + m(0,1);
+	std::cout << m << std::endl;
 }

kernel_module/user/eigen_svd.cpp

@@ -0,0 +1,24 @@
+/* Adapted from: https://eigen.tuxfamily.org/dox/classEigen_1_1JacobiSVD.html */
+
+#include <iostream>
+using std::cout;
+using std::endl;
+
+#include <Eigen/Core>
+#include <Eigen/SVD>
+using Eigen::ComputeThinU;
+using Eigen::ComputeThinV;
+using Eigen::JacobiSVD;
+using Eigen::MatrixXf;
+using Eigen::Vector3f;
+
+int main() {
+	MatrixXf m = MatrixXf::Random(3,2);
+	JacobiSVD<MatrixXf> svd(m, ComputeThinU | ComputeThinV);
+	Vector3f rhs(1, 0, 0);
+	cout << "m = " << endl << m << endl << endl;
+	cout << "svd.singularValues() = " << endl << svd.singularValues() << endl << endl;
+	cout << "svd.MatrixU() = " << endl << svd.matrixU() << endl << endl;
+	cout << "svd.MatrixV() = " << endl << svd.matrixV() << endl << endl;
+	cout << "svd.solve() = " << endl << svd.solve(rhs) << endl << endl;
+}