Changeset 759a6a for src

Timestamp:

May 2, 2012, 1:36:49 PM (14 years ago)

Author:

Julian Iseringhausen <isering@…>

Children:

6fee21

Parents:

728149

Message:

Unrolled loops for evaluating polynomials with Horner scheme.

git-svn-id: ​https://svn.version.fz-juelich.de/scafacos/trunk@1780 5161e1c8-67bf-11de-9fd5-51895aff932f

File:

• src/base/polynomial.hpp (modified) (1 diff)

src/base/polynomial.hpp

@@ -42 +42 @@
   vmg_float operator()(const vmg_float& val) const
   {
-    vmg_float result = coeff.back();
-    for (int i=coeff.size()-2; i>=0; --i)
-      result = coeff[i] + result * val;
-    return result;
+    switch (coeff.size())
+      {
+      case 1:
+        return coeff[0];
+      case 2:
+        return coeff[1] * val + coeff[0];
+      case 3:
+        return (coeff[2] * val + coeff[1]) * val + coeff[0];
+      case 4:
+        return ((coeff[3] * val + coeff[2]) * val + coeff[1]) * val + coeff[0];
+      case 5:
+        return (((coeff[4] * val + coeff[3]) * val + coeff[2]) * val + coeff[1]) * val + coeff[0];
+      case 6:
+        return ((((coeff[5] * val + coeff[4]) * val + coeff[3]) * val + coeff[2]) * val + coeff[1]) * val + coeff[0];
+      case 7:
+        return (((((coeff[6]*val+coeff[5])*val+coeff[4])*val+coeff[3])*val+coeff[2])*val+coeff[1])*val+coeff[0];
+      case 8:
+        return ((((((coeff[7]*val+coeff[6])*val+coeff[5])*val+coeff[4])*val+coeff[3])*val+coeff[2])*val+coeff[1])*val+coeff[0];
+      default:
+        vmg_float result = coeff.back();
+        for (int i=coeff.size()-2; i>=0; --i)
+          result = coeff[i] + result * val;
+        return result;
+      }
+
   }