Merge pull request #298 from jgray-19/survey_fixes

Survey fixes for rbend

Author: ldeniau

src/madl_esurv.mad

@@ -36,8 +36,9 @@ local fnil, bind3rd          in MAD.gfunc
 local errorf                 in MAD.utility
 local minlen, minang         in MAD.constant
 local is_implicit            in element.drift
+local arc2cord               in MAD.gmath
 
-local abs                    in math
+local abs, sin               in math
 
 -- integrator schemes ---------------------------------------------------------o
 
@@ -192,23 +193,23 @@ end
 -- rbend special --------------------------------------------------------------o
 
 local function fng_e1 (e, m, s)
-  local e1, e2, sdir in m
+  local e1, e2, elc, sdir in m
   local d = s*sdir
   if d == -1 then
-    local e_ = {name=e.name, dx=m.elc*sin((e2-e1)/2), dy=0, ds=0}
-    yrotation(e2, m, -1)
-    translate(e_, m,  s)
+    local e_ = {name=e.name, dx=elc*sin((e2-e1)/2), dy=0, ds=0}
+    yrotation(e2, m, -1) -- translation independant of direction
+    translate(e_, m, -1)
   elseif e1 ~= 0 then
     yrotation(e1, m, -1)
   end
 end
 
 local function fng_e2 (e, m, s)
-  local e1, e2, sdir in m
+  local e1, e2, elc, sdir in m
   local d = s*sdir
   if d == 1 then
-    local e_ = {name=e.name, dx=m.elc*sin((e2-e1)/2), dy=0, ds=0}
-    translate(e_, m,  s)
+    local e_ = {name=e.name, dx=elc*sin((e2-e1)/2), dy=0, ds=0}
+    translate(e_, m, -1) -- translation independant of direction
     yrotation(e1, m, -1)
   elseif e2 ~= 0 then
     yrotation(e2 , m, -1)
@@ -221,18 +222,23 @@ local function track_rbend (elm, m)
   local fng = nil -- default: curved rbend aka sbend with parallel pole faces
 
   if elm.true_rbend then -- true rbend
-    local e1, e2 in elm
-    -- compute correct E1 and E2 from the slides.
-    if e1 and e2 then
+    local e1, e2, angle, l in elm
+    if e1 and e2 then -- MAD-like Wedge rbend
       fng = fng_e
-    elseif e1 then
-      fng = fng_e1
-    else
-      fng = fng_e2
+    else              -- true parallel rbend
+      m.elc = arc2cord(l, angle)
+      if e1 then
+        m.e1, m.e2 = e1, angle - e1
+        fng = fng_e1
+      else
+        m.e1, m.e2 = angle - e2, e2
+        fng = fng_e2
+      end
     end
   end
 
   track_thick(elm, m, fng)
+  m.e1, m.e2, m.elc = nil, nil, nil
 end
 
 -- load maps into elements ----------------------------------------------------o