Add a skeleton of C API for Eigen3.

Title says pretty much everything. For now, only thing available is a solver of eigen
values/vectors for self-adjoint matrices.

We can easily add more when needed.

Thanks to Sergey and Campbell for quick review.

1 files changed, 40 insertions, 0 deletions

diff --git a/extern/Eigen3/intern/eigenvalues.h b/extern/Eigen3/intern/eigenvalues.h
new file mode 100644
index 00000000000..93fc06c2339
--- /dev/null
+++ b/extern/Eigen3/intern/eigenvalues.h
@@ -0,0 +1,40 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2015 Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Blender Foundation,
+ *                 Bastien Montagne
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#ifndef __EIGEN3_EIGENVALUES_C_API_H__
+#define __EIGEN3_EIGENVALUES_C_API_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+bool EG3_self_adjoint_eigen_solve(const int size, const float *matrix, float *r_eigen_values, float *r_eigen_vectors);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* __EIGEN3_EIGENVALUES_C_API_H__ */