Bug 87177

Summary: equations are incorrectly re-sampled
Product: [Applications] kst Reporter: Netterfield <netterfield>
Component: generalAssignee: kst
Status: RESOLVED FIXED    
Severity: normal    
Priority: NOR    
Version: 1.x   
Target Milestone: ---   
Platform: unspecified   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description Netterfield 2004-08-14 03:23:04 UTC 
Version:           0.99-devel (using KDE 3.2 BRANCH >= 20040204, Mandrake Linux Cooker i586 - Cooker)
Compiler:          gcc version 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)
OS:                Linux (i686) release 2.6.3-7mdk

In equations, the length of the equation vectors is the desired length-1.  So if vectors of length 10 are used as the input X vector and in the equation,then the equation will have length 9, and will be resampled....

This really confused us today using kst to debug something else, so it is a pretty serious problem.  The patch is trival, and I will submit it next.
Comment 1 Netterfield 2004-08-16 16:47:57 UTC 
The patch I submitted earlier fixes the case where NS_i == int(a)NS_j.

But this is rarely the case.  More often, for RVectors
NS_i = int(a)(NS_j-SPF) + 1 
So that the 1st and last samples correspond properly.

Fixing it will be non-trival, but I think it is pretty important.

Thoughts?
Comment 2 Netterfield 2004-08-17 05:18:04 UTC 
CVS commit by netterfield: 

fix for [Bug 87177] equations are incorrectly re-sampled

CCMAIL: 87177-done@bugs.kde.org


  M +5 -10     kstequationcurve.cpp   1.61.2.1


--- kdeextragear-2/kst/kst/kstequationcurve.cpp  #1.61:1.61.2.1
@@ -371,16 +371,11 @@ bool KstEquationCurve::FillY(bool force)
       }
     }
-    if ((*_xVector)->sampleCount() > 0) {
-      _interp = (ns+1) / (*_xVector)->sampleCount();
-    } else { // avoid divide by zero
-      _interp = 1;
-    }
   } else {
-    _interp = 1;
+    ns = (*_xVector)->sampleCount();
   }
 
-  if (NS != (*_xVector)->sampleCount() || _interp != 1 ||
+  if (NS != (*_xVector)->sampleCount() || (ns != (*_xVector)->sampleCount()) ||
       (*_xVector)->numShift() != (*_xVector)->numNew()) {
-    NS = (*_xVector)->sampleCount()*_interp;// - 1;
+    NS = ns;
 
     KstVectorPtr yv = *_yVector;
@@ -395,6 +390,6 @@ bool KstEquationCurve::FillY(bool force)
     // calculate shift and new samples
     // only do shift optimization if all used vectors are same size and shift
-    v_shift = (*_xVector)->numShift()*_interp;
-    v_new = (*_xVector)->numNew()*_interp;
+    v_shift = (*_xVector)->numShift();
+    v_new = (*_xVector)->numNew();
 
     for (i_v = 0; i_v < VectorsUsed.count(); i_v++) {