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authorTavian Barnes <tavianator@gmail.com>2010-10-26 15:42:13 -0400
committerTavian Barnes <tavianator@gmail.com>2010-10-26 15:42:13 -0400
commit0075e0c37d9c33ed00e4308e6444b61b204327ba (patch)
tree4c112619d917fc8374715bde8ce4e4f0e6723892 /libdimension/dimension
parent1fba91c6fe9115be67929ce1e247dd759a21fcd1 (diff)
downloaddimension-0075e0c37d9c33ed00e4308e6444b61b204327ba.tar.xz
Add numerical polynomial solver based on Uspensky's algorithm.
Diffstat (limited to 'libdimension/dimension')
-rw-r--r--libdimension/dimension/geometry.h7
-rw-r--r--libdimension/dimension/polynomial.h51
2 files changed, 58 insertions, 0 deletions
diff --git a/libdimension/dimension/geometry.h b/libdimension/dimension/geometry.h
index 87e7ab7..4c4f8b8 100644
--- a/libdimension/dimension/geometry.h
+++ b/libdimension/dimension/geometry.h
@@ -96,6 +96,13 @@ dmnsn_degrees(double radians)
return radians*45.0/atan(1.0);
}
+DMNSN_INLINE int
+dmnsn_signbit(double n)
+{
+ /* Guarantee a 1 or 0 return, to allow testing two signs for equality */
+ return signbit(n) ? 1 : 0;
+}
+
/* Shorthand for vector/matrix construction */
DMNSN_INLINE dmnsn_vector
diff --git a/libdimension/dimension/polynomial.h b/libdimension/dimension/polynomial.h
new file mode 100644
index 0000000..52a44dd
--- /dev/null
+++ b/libdimension/dimension/polynomial.h
@@ -0,0 +1,51 @@
+/*************************************************************************
+ * Copyright (C) 2009-2010 Tavian Barnes <tavianator@gmail.com> *
+ * *
+ * This file is part of The Dimension Library. *
+ * *
+ * The Dimension Library is free software; you can redistribute it and/ *
+ * or modify it under the terms of the GNU Lesser General Public License *
+ * as published by the Free Software Foundation; either version 3 of the *
+ * License, or (at your option) any later version. *
+ * *
+ * The Dimension Library 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 *
+ * Lesser General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU Lesser General Public *
+ * License along with this program. If not, see *
+ * <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+/*
+ * Utility functions for working with and numerically solving polynomials.
+ * Polynomials are represented as simple arrays where the ith element is the
+ * coefficient on x^i. In general, we are only interested in positive roots.
+ */
+
+#ifndef DIMENSION_POLYNOMIAL_H
+#define DIMENSION_POLYNOMIAL_H
+
+#include <stddef.h>
+#include <stdio.h>
+
+DMNSN_INLINE double
+dmnsn_evaluate_polynomial(double poly[], size_t degree, double x)
+{
+ double ret = poly[degree];
+ ssize_t i;
+ for (i = degree - 1; i >= 0; --i) {
+ ret = ret*x + poly[i];
+ }
+ return ret;
+}
+
+/* Stores the non-negative roots of poly[] in x[], and returns the number of
+ such roots that were stored */
+size_t dmnsn_solve_polynomial(double poly[], size_t degree, double x[]);
+
+/* Helper function to print a polynomial */
+void dmnsn_print_polynomial(FILE *file, double poly[], size_t degree);
+
+#endif /* DIMENSION_POLYNOMIAL_H */