From 29f364d4753ea10b84607e65c8f922f79d41d357 Mon Sep 17 00:00:00 2001
From: Holger Vogt <holger.vogt@uni-due.de>
Date: Sat, 26 Jan 2019 09:48:30 +0100
Subject: [PATCH] creating a linearized cutout of the original vector by
 defining the vectors lin-tstart, lin-tstop, and lin-tstep before issuing the
 'linearize' command

---
 src/frontend/linear.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/frontend/linear.c b/src/frontend/linear.c
index 749481f47..7cb7d2512 100644
--- a/src/frontend/linear.c
+++ b/src/frontend/linear.c
@@ -17,6 +17,8 @@ Author: 1985 Wayne A. Christopher, U. C. Berkeley CAD Group
  * we determine by looking at the transient parameters in the CKT struct.
  * If no circuit is loaded, e.g. because the 'load' command has been used
  * to obtain data, try to get parameters from scale vector.
+ * Interpolation may be restricted to only a region of the input vector,
+ * thus creating a cutout of the original vector.
  */
 
 void
@@ -26,6 +28,7 @@ com_linearize(wordlist *wl)
     struct plot *new, *old;
     struct dvec *newtime, *v;
     struct dvec *oldtime;
+    struct dvec *lin;
     int len, i;
 
     if (!plot_cur || !plot_cur->pl_dvecs || !plot_cur->pl_scale) {
@@ -54,9 +57,33 @@ com_linearize(wordlist *wl)
             fprintf(cp_err, "Error: no data in vector\n");
             return;
         }
-        tstart = plot_cur->pl_scale->v_realdata[0];
-        tstop = plot_cur->pl_scale->v_realdata[length - 1];
-        tstep = (tstop - tstart) / (double)length;
+
+        /* if this plot contains special vectors lin-tstart, lin-tstop and lin-tstep use these instead */
+        lin = vec_fromplot("lin-tstart", plot_cur);
+        if (lin) {
+            fprintf(cp_out, "linearize tstart is set to: %8e\n", lin->v_realdata[0]);
+            tstart = lin->v_realdata[0];
+        }
+        else {
+            tstart = plot_cur->pl_scale->v_realdata[0];
+        }
+        lin = vec_fromplot("lin-tstop", plot_cur);
+        if (lin) {
+            fprintf(cp_out, "linearize tstop is set to: %8e\n", lin->v_realdata[0]);
+            tstop = lin->v_realdata[0];
+        }
+        else {
+            tstop = plot_cur->pl_scale->v_realdata[length - 1];
+        }
+        lin = vec_fromplot("lin-tstep", plot_cur);
+        if (lin) {
+            fprintf(cp_out, "linearize tstep is set to: %8e\n", lin->v_realdata[0]);
+            tstep = lin->v_realdata[0];
+        }
+        else {
+            tstep = (tstop - tstart) / (double)length;
+        }
+
     }
     /* finally check if tstart, tstop and tstep are reasonable */
     if (((tstop - tstart) * tstep <= 0.0) || ((tstop - tstart) < tstep)) {