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mc_work/dorun.go

@@ -175,15 +175,24 @@ func saveBest(x []float32, fTrial float64, n int) {
 }
 
 // saveStep is called when we accept a change. It writes or saves for
-// later plotting.
+// later plotting. The plan, every time we append values, we have to do it twice
+// so we get a proper stepped appearance.
 func saveStep(cprm *cprm, n int, tmprtr float64, x []float32, fTrial float64) {
 	saveBest(x, fTrial, n)
-	cprm.plotnstp = append(cprm.plotnstp, float64(n)) // num steps
-	if cprm.fplotWrt != nil {                         // Function values  // function values
-		cprm.plotf = append(cprm.plotf, fTrial)
-		cprm.plotTmprtr = append(cprm.plotTmprtr, tmprtr)
+	fprev := fTrial
+	xprev := x
+	if n != 0 {
+		fprev = cprm.plotf[len(cprm.plotf)-1]
+		xprev = cprm.plotXtrj[len(cprm.plotXtrj)-len(x):]
+	}
+	cprm.plotnstp = append(cprm.plotnstp, float64(n), float64(n)) // num steps
+	if cprm.fplotWrt != nil {                         // Function values
+		cprm.plotf = append(cprm.plotf, fprev) // copy the last coordinates
+		cprm.plotf = append(cprm.plotf, fTrial) // and append them
+		cprm.plotTmprtr = append(cprm.plotTmprtr, tmprtr) // then the new ones
 	}
 	if cprm.xplotWrt != nil { // The trajectory
+		cprm.plotXtrj = append(cprm.plotXtrj, xprev...)
 		cprm.plotXtrj = append(cprm.plotXtrj, x...)
 	}
 	if cprm.doTxtFval {