From ca1daeb5270d86590ea9af9db917de2e02acb657 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Thu, 8 Feb 2018 10:29:51 +0100
Subject: [PATCH] [apps] Sequence: fix confusion between sequence index in
 store and sequence name

---
 apps/sequence/sequence_context.cpp |  9 ++++-
 apps/sequence/test/sequence.cpp    | 57 ++++++++++++++++++++----------
 2 files changed, 46 insertions(+), 20 deletions(-)

diff --git a/apps/sequence/sequence_context.cpp b/apps/sequence/sequence_context.cpp
index 7e1c73995..fce83df19 100644
--- a/apps/sequence/sequence_context.cpp
+++ b/apps/sequence/sequence_context.cpp
@@ -53,8 +53,15 @@ void TemplatedSequenceContext<T>::step(SequenceStore * sequenceStore, SequenceCo
   u = u && u->isDefined() ? u : nullptr;
   Sequence * v = sequenceStore->numberOfFunctions() > 1 ? sequenceStore->functionAtIndex(1) : nullptr;
   v = v && v->isDefined() ? v : nullptr;
+  /* Switch u & v  if the name of u is v */
+  if (u != nullptr && u->name()[0] ==  SequenceStore::k_sequenceNames[1][0]) {
+    Sequence * temp = u;
+    u = v;
+    v = temp;
+  }
 
-  /* TODO: explain */
+  /* Approximate u & v at the new rank. We evaluate u twice in case its
+   * expression depends on v. */
   m_values[0][0] = u ? u->approximateToNextRank<T>(m_rank, sqctx) : NAN;
   m_values[1][0] = v ? v->approximateToNextRank<T>(m_rank, sqctx) : NAN;
   m_values[0][0] = u ? u->approximateToNextRank<T>(m_rank, sqctx) : NAN;
diff --git a/apps/sequence/test/sequence.cpp b/apps/sequence/test/sequence.cpp
index d02a5f887..20df756f8 100644
--- a/apps/sequence/test/sequence.cpp
+++ b/apps/sequence/test/sequence.cpp
@@ -14,34 +14,45 @@ void check_sequences_defined_by(double result[2][10], Sequence::Type typeU, cons
   SequenceStore store;
   SequenceContext sequenceContext(&globalContext, &store);
 
-  Sequence * u = store.addEmptyFunction();
-  Sequence * v = store.addEmptyFunction();
-  u->setType(typeU);
+  Sequence * u = nullptr;
+  Sequence * v = nullptr;
   if (definitionU) {
+    u = store.addEmptyFunction();
+    assert(u->name()[0] == 'u');
+    u->setType(typeU);
     u->setContent(definitionU);
+    if (conditionU1) {
+      u->setFirstInitialConditionContent(conditionU1);
+    }
+    if (conditionU2) {
+      u->setSecondInitialConditionContent(conditionU2);
+    }
   }
-  if (conditionU1) {
-    u->setFirstInitialConditionContent(conditionU1);
-  }
-  if (conditionU2) {
-    u->setSecondInitialConditionContent(conditionU2);
-  }
-  v->setType(typeV);
   if (definitionV) {
+    if (store.numberOfFunctions() == 0) {
+      Sequence * tempU = store.addEmptyFunction();
+      v = store.addEmptyFunction();
+      store.removeFunction(tempU);
+      v = store.functionAtIndex(0);
+    } else {
+      assert(store.numberOfFunctions() == 1);
+      v = store.addEmptyFunction();
+    }
+    v->setType(typeV);
     v->setContent(definitionV);
-  }
-  if (conditionV1) {
-    v->setFirstInitialConditionContent(conditionV1);
-  }
-  if (conditionV2) {
-    v->setSecondInitialConditionContent(conditionV2);
+    if (conditionV1) {
+      v->setFirstInitialConditionContent(conditionV1);
+    }
+    if (conditionV2) {
+      v->setSecondInitialConditionContent(conditionV2);
+    }
   }
   for (int j = 0; j < 10; j++) {
-    if (u->isDefined()) {
+    if (u && u->isDefined()) {
       double un = u->evaluateAtAbscissa((double)j, &sequenceContext);
       assert((std::isnan(un) && std::isnan(result[0][j])) || (un == result[0][j]));
     }
-    if (v->isDefined()) {
+    if (v && v->isDefined()) {
       double vn = v->evaluateAtAbscissa((double)j, &sequenceContext);
       assert((std::isnan(vn) && std::isnan(result[1][j])) || (vn == result[1][j]));
     }
@@ -134,6 +145,14 @@ QUIZ_CASE(sequence_evaluation) {
   // u(n+2) = v(n+1)+u(n+1)+v(n)+u(n)+n, u(1) = 0, u(0) = 0; v(n+1) = u(n)+n, v(0)=0
   double result17[2][10] = {{0.0, 0.0, 0.0, 2.0, 7.0, 19.0, 46.0, 105.0, 233.0, 509.0}, {0.0, 0.0, 1.0, 2.0, 5.0, 11.0, 24.0, 52.0, 112.0, 241.0}};
   check_sequences_defined_by(result17, Sequence::Type::DoubleRecurrence, "v(n+1)+v(n)+u(n+1)+u(n)+n", "0", "0", Sequence::Type::SingleRecurrence, "u(n)+n", "0");
-  }
+
+  // u(n) = n; v undefined
+  double result18[2][10] = {{0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0}, {NAN, NAN, NAN, NAN, NAN, NAN, NAN, NAN, NAN, NAN}};
+  check_sequences_defined_by(result18, Sequence::Type::Explicit, "n");
+
+  // u undefined; v(n) = n
+  double result19[2][10] = {{NAN, NAN, NAN, NAN, NAN, NAN, NAN, NAN, NAN, NAN}, {0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0}};
+  check_sequences_defined_by(result19, Sequence::Type::Explicit, nullptr, nullptr, nullptr, Sequence::Type::Explicit, "n");
+}
 
 }