diff --git a/doc/xschem_man/xschem_man.html b/doc/xschem_man/xschem_man.html
index 2f7ace3c..549865ab 100644
--- a/doc/xschem_man/xschem_man.html
+++ b/doc/xschem_man/xschem_man.html
@@ -78,6 +78,7 @@
  <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/xschem_embedded_simulation.mp4">[Video] See logic propagation of nets live in xschem without using a backend simulator</a></li>
  <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/xschem_graphs.mp4">[Video]  View Ngspice/Xyce simulation data inside XSCHEM</a></li>
  <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/live_annotation_with_b_cursor.mp4">[Video] Live annotation of simulation values into the schematic</a></li>
+ <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/expr_in_graphs.mp4">[Video] Setting up a Xyce simulation, viewing results and doing math on graphs</a></li>
  <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/probe_to_gaw.mp4">[Video] Probe xschem nets into the GAW waveform viewer</a></li>
  <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/probe_to_bespice.mp4">[Video] Probe xschem nets into the BESPICE waveform viewer</a></li>
  <li><a href="https://xschem.sourceforge.io/stefan/xschem_man/video_tutorials/create_symbol.mp4">[Video] Creating a symbol</a></li>
diff --git a/src/save.c b/src/save.c
index 94760efb..6b1c8667 100644
--- a/src/save.c
+++ b/src/save.c
@@ -761,20 +761,22 @@ int plot_raw_custom_data(int sweep_idx, int first, int last, const char *expr)
       if(stackptr2 > 1) { /* 2 argument operators */
         switch(stack1[i].i) {
           case PLUS:
-            stack2[stackptr2 - 2] =  stack2[stackptr2 - 2] + stack2[stackptr2 - 1];
+            stack2[stackptr2 - 2] = stack2[stackptr2 - 2] + stack2[stackptr2 - 1];
             stackptr2--;
             break;
           case MINUS:
-            stack2[stackptr2 - 2] =  stack2[stackptr2 - 2] - stack2[stackptr2 - 1];
+            stack2[stackptr2 - 2] = stack2[stackptr2 - 2] - stack2[stackptr2 - 1];
             stackptr2--;
             break;
           case MULT:
-            stack2[stackptr2 - 2] =  stack2[stackptr2 - 2] * stack2[stackptr2 - 1];
+            stack2[stackptr2 - 2] = stack2[stackptr2 - 2] * stack2[stackptr2 - 1];
             stackptr2--;
             break;
           case DIVIS:
             if(stack2[stackptr2 - 1]) {
-              stack2[stackptr2 - 2] =  stack2[stackptr2 - 2] / stack2[stackptr2 - 1];
+              stack2[stackptr2 - 2] = stack2[stackptr2 - 2] / stack2[stackptr2 - 1];
+            } else if(stack2[stackptr2 - 2] == 0.0) {
+              stack2[stackptr2 - 2] = 0;
             } else {
               stack2[stackptr2 - 2] =  y[p - 1];
             }
diff --git a/src/xschem.tcl b/src/xschem.tcl
index c68a53b5..e3983950 100644
--- a/src/xschem.tcl
+++ b/src/xschem.tcl
@@ -657,6 +657,9 @@ proc sim_is_ngspice {} {
   return 0
 }
 
+proc sim_is_Xyce {} {
+  return [sim_is_xyce]
+}
 
 proc sim_is_xyce {} {
   global sim