xgraph bug

[Patrik Fors <Patrik.Fors@lu.erisoft.se>]

I found a small bug/typo in xgraph. It's mentioned on the 'Installation
Problems, Bug
Fixes, and Help' page but I couldnt find any fix there.
Anyway, xgraph crashed on examples/surface*  in derivative.c..

..and the bug/typo was found on line #96 (in derivative.c)

    92        if (theList) {
    93          D1List->next = (PointList *)malloc(sizeof(PointList));
    94          D2List->next = (PointList *)malloc(sizeof(PointList));
    95          D1List = D1List->next;
    96          D2List = D1List->next;

should (of course) be

    92        if (theList) {
    93          D1List->next = (PointList *)malloc(sizeof(PointList));
    94          D2List->next = (PointList *)malloc(sizeof(PointList));
    95          D1List = D1List->next;
    96          D2List = D2List->next;


Patrik Fors.