update to trunk

(bzr r13879.1.17)

1 files changed, 13 insertions, 5 deletions

diff --git a/src/2geom/sbasis.cpp b/src/2geom/sbasis.cpp
index b56e03c74..42d92d7b8 100644
--- a/src/2geom/sbasis.cpp
+++ b/src/2geom/sbasis.cpp
@@ -328,9 +328,9 @@ SBasis derivative(SBasis const &a) {
     }
     int k = a.size()-1;
     double d = (2*k+1)*(a[k][1] - a[k][0]);
-    if(d == 0)
+    if (d == 0 && k > 0) {
         c.pop_back();
-    else {
+    } else {
         c[k][0] = d;
         c[k][1] = d;
     }
@@ -351,9 +351,9 @@ void SBasis::derive() { // in place version
     }
     int k = size()-1;
     double d = (2*k+1)*((*this)[k][1] - (*this)[k][0]);
-    if(d == 0)
+    if (d == 0 && k > 0) {
         pop_back();
-    else {
+    } else {
         (*this)[k][0] = d;
         (*this)[k][1] = d;
     }
@@ -466,6 +466,15 @@ SBasis compose(SBasis const &a, SBasis const &b, unsigned k) {
     return r;
 }
 
+SBasis portion(const SBasis &t, double from, double to) {
+    double fv = t.valueAt(from);
+    double tv = t.valueAt(to);
+    SBasis ret = compose(t, Linear(from, to));
+    ret.at0() = fv;
+    ret.at1() = tv;
+    return ret;
+}
+
 /*
 Inversion algorithm. The notation is certainly very misleading. The
 pseudocode should say:
@@ -632,7 +641,6 @@ SBasis compose_inverse(SBasis const &f, SBasis const &g, unsigned order, double
 
         //TODO: handle det~0!!
         if (fabs(det)<zero){
-            det = zero;
             a=b=0;
         }else{
             a=( q01*r10-q10*r01)/det;