From 0b7572e55936977d9ce91c0e0932939708776161 Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@drexel.edu>
Date: Wed, 2 Jun 2010 01:21:31 -0400
Subject: [PATCH] Flip deflection sign for hooke.driver.wtk.

We want +deflection for +chain tension.
---
 hooke/driver/wtk.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hooke/driver/wtk.py b/hooke/driver/wtk.py
index 46bf92e..640f056 100644
--- a/hooke/driver/wtk.py
+++ b/hooke/driver/wtk.py
@@ -185,7 +185,11 @@ class WTKDriver (Driver):
             * info['z piezo sensitivity (m/V)']
             )
 
-        ret[:,d_scol] = (
+        # Leading '-' because deflection voltage increases as the tip
+        # moves away from the surface, but it makes more sense to me
+        # to have it increase as it moves toward the surface (positive
+        # tension on the protein chain).
+        ret[:,d_scol] = -(
             (data[:,d_rcol]
              * info['deflection sensitivity (V/bit)']
              - info['deflection offset (V)'])
-- 
2.26.2