Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nurbs-1.3.6 / private / onebasisfun__.m

diff --git a/octave_packages/nurbs-1.3.6/private/onebasisfun__.m b/octave_packages/nurbs-1.3.6/private/onebasisfun__.m
new file mode 100644 (file)
index 0000000..bbd1764
--- /dev/null
+++ b/octave_packages/nurbs-1.3.6/private/onebasisfun__.m
@@ -0,0 +1,56 @@
+function Nip = onebasisfun__ (u, p, U)
+
+%  __ONEBASISFUN__: Undocumented internal function
+%
+%   Adapted from Algorithm A2.4 from 'The NURBS BOOK' pg74.
+%
+%   Copyright (C) 2009 Carlo de Falco
+%   Copyright (C) 2012 Rafael Vazquez
+%   This software comes with ABSOLUTELY NO WARRANTY; see the file
+%   COPYING for details.  This is free software, and you are welcome
+%   to distribute it under the conditions laid out in COPYING.
+
+  Nip = zeros (size (u));
+  N = zeros (p+1, 1);
+
+  for ii = 1:numel(u)
+    if ((u(ii) == U(1)) && (U(1) == U(end-1)) || ...
+        (u(ii) == U(end)) && (U(end) == U(2)))
+      Nip(ii) = 1;
+      continue
+    end
+    if (~ any (U <= u(ii))) || (~ any (U > u(ii)))
+      continue;
+    end
+    for jj = 1:p+1 % Initialize zero-th degree functions
+      if (u(ii) > U(jj) && u(ii) < U(jj+1))
+        N(jj) = 1;
+      else
+        N(jj) = 0;
+      end
+    end
+    for k = 1:p
+      if (N(1) == 0)
+        saved = 0;
+      else
+        saved = (u(ii) - U(1))*N(1) / (U(k+1)-U(1));
+      end
+
+      for jj = 1:p-k+1
+        Uleft = U(1+jj);
+        Uright = U(1+jj+k);
+        if (N(jj+1) == 0)
+          N(jj) = saved;
+          saved = 0;
+        else
+          temp = N(jj+1)/(Uright-Uleft);
+          N(jj) = saved + (Uright - u(ii))*temp;
+          saved = (u(ii) - Uleft)*temp;
+        end
+      end
+    end
+    Nip(ii) = N(1);
+  end
+
+
+end