Fix delay derivative (#11975)

OpenModelica · Feb 10, 2024 · 08f57e1 · 08f57e1
1 parent 9a763fc
commit 08f57e1
Showing 1 changed file with 16 additions and 20 deletions.
diff --git a/OMCompiler/Compiler/BackEnd/Differentiate.mo b/OMCompiler/Compiler/BackEnd/Differentiate.mo
@@ -1783,7 +1783,6 @@ algorithm
                 e1,
                 DAE.BINARY(res1, DAE.DIV(tp), DAE.BINARY(DAE.RCONST(1.0), DAE.ADD(tp), DAE.BINARY(e2, DAE.MUL(tp),e2)))
                ));
-
       then
         (res2,  funcs);
 
@@ -1849,25 +1848,22 @@ algorithm
 
     case ("delay", {_, e2, e3, e4}, DAE.CALL_ATTR(ty=tp))
       algorithm
-        // 1. differentiate delayed expression
-        (e, funcs) := differentiateExp(e2, inDiffwrtCref, inInputData, inDiffType, inFunctionTree, maxIter);
-        // 2. filter all seeds from e
-        seeds := list(cref for cref guard(isSeedCref(cref)) in Expression.extractUniqueCrefsFromExp(e, false));
-        // 3. create empty replacement rules
-        repl := BackendVarTransform.emptyReplacements();
-        repl := BackendVarTransform.addReplacements(repl, seeds, List.fill(DAE.ICONST(0), listLength(seeds)), NONE());
-        res := DAE.RCONST(0);
-        // 4. create delayed expression for each seed and multiply each delayed with corresponding seed and create sum
-        for seed in seeds loop
-          repl := BackendVarTransform.addReplacement(repl, seed, DAE.ICONST(1), NONE());
-          // create call with seed replaced by 1 and all other seeds replaced by 0
-          (res1, _) := BackendVarTransform.replaceExp(e, repl, NONE());
-          res1 := DAE.CALL(Absyn.IDENT(name), {DAE.ICONST(-1), res1, e3, e4}, inAttr);
-          // multiply call with correspondings seed and add to rest
-          res := DAE.BINARY(DAE.BINARY(DAE.CREF(seed, tp), DAE.MUL(tp), res1), DAE.ADD(tp), res);
-          repl := BackendVarTransform.addReplacement(repl, seed, DAE.ICONST(0), NONE());
-        end for;
-        (res, _) := ExpressionSimplify.simplify(res);
+        res1 := match inDiffType
+          case BackendDAE.DIFFERENTIATION_TIME()  then DAE.RCONST(1.0);
+                                                  else DAE.RCONST(0.0);
+        end match;
+        (res2, funcs) := differentiateExp(e3, inDiffwrtCref, inInputData, inDiffType, inFunctionTree, maxIter);
+        res2 := DAE.BINARY(res1, DAE.SUB(tp), res2);
+        (res2, _) := ExpressionSimplify.simplify(res2);
+        if Expression.isZero(res2) then
+          res := Expression.makeZeroExpression(Expression.arrayDimension(tp));
+        else
+          // differentiate delayed expression w.r.t. time
+          (e, funcs) := differentiateExp(e2, inDiffwrtCref, inInputData, BackendDAE.DIFFERENTIATION_TIME(), funcs, maxIter);
+          e := DAE.CALL(Absyn.IDENT(name), {DAE.ICONST(-1), e, e3, e4}, inAttr);
+          res := DAE.BINARY(res2, DAE.MUL(tp), e);
+          (res, _) := ExpressionSimplify.simplify(res);
+        end if;
       then
         (res, funcs);