From a0ae31f0d475e5aa7e5d5c853fcbc56e229a6f90 Mon Sep 17 00:00:00 2001
From: Tyler Veness <calcmogul@gmail.com>
Date: Sun, 29 Dec 2024 11:57:28 -0800
Subject: [PATCH] Remove operator^ from Matrix and SubgraphPreconditioner

Eigen recently added an operator^ for coefficient-wise bitwise xor,
which conflicts with gtsam's operator^. Since gtsam's operator^ isn't
xor, I opted to remove it.

Fixes #1951.
---
 gtsam/base/Matrix.cpp                   | 11 -----------
 gtsam/base/Matrix.h                     |  6 ------
 gtsam/linear/SubgraphPreconditioner.cpp | 14 --------------
 gtsam/linear/SubgraphPreconditioner.h   |  3 ---
 gtsam/linear/iterative.h                |  7 +------
 5 files changed, 1 insertion(+), 40 deletions(-)

diff --git a/gtsam/base/Matrix.cpp b/gtsam/base/Matrix.cpp
index 1e04bc58a..6248ad77d 100644
--- a/gtsam/base/Matrix.cpp
+++ b/gtsam/base/Matrix.cpp
@@ -126,17 +126,6 @@ bool linear_dependent(const Matrix& A, const Matrix& B, double tol) {
 }
 
 /* ************************************************************************* */
-Vector operator^(const Matrix& A, const Vector & v) {
-  if (A.rows()!=v.size()) {
-    throw std::invalid_argument("Matrix operator^ : A.m(" + std::to_string(A.rows()) + ")!=v.size(" +
-                                std::to_string(v.size()) + ")");
-  }
-//  Vector vt = v.transpose();
-//  Vector vtA = vt * A;
-//  return vtA.transpose();
-  return A.transpose() * v;
-}
-
 const Eigen::IOFormat& matlabFormat() {
   static const Eigen::IOFormat matlab(
     Eigen::StreamPrecision, // precision
diff --git a/gtsam/base/Matrix.h b/gtsam/base/Matrix.h
index c8dc46ed5..2b177e3d7 100644
--- a/gtsam/base/Matrix.h
+++ b/gtsam/base/Matrix.h
@@ -132,12 +132,6 @@ GTSAM_EXPORT bool linear_independent(const Matrix& A, const Matrix& B, double to
  */
 GTSAM_EXPORT bool linear_dependent(const Matrix& A, const Matrix& B, double tol = 1e-9);
 
-/**
- * overload ^ for trans(A)*v
- * We transpose the vectors for speed.
- */
-GTSAM_EXPORT Vector operator^(const Matrix& A, const Vector & v);
-
 /** products using old-style format to improve compatibility */
 template<class MATRIX>
 inline MATRIX prod(const MATRIX& A, const MATRIX&B) {
diff --git a/gtsam/linear/SubgraphPreconditioner.cpp b/gtsam/linear/SubgraphPreconditioner.cpp
index 53ea94d6e..9087b3c90 100644
--- a/gtsam/linear/SubgraphPreconditioner.cpp
+++ b/gtsam/linear/SubgraphPreconditioner.cpp
@@ -149,20 +149,6 @@ void SubgraphPreconditioner::multiplyInPlace(const VectorValues& y, Errors& e) c
   Ab2_.multiplyInPlace(x, ei);                  // use iterator version
 }
 
-/* ************************************************************************* */
-// Apply operator A', A'*e = [I inv(R1')*A2']*e = e1 + inv(R1')*A2'*e2
-VectorValues SubgraphPreconditioner::operator^(const Errors& e) const {
-
-  Errors::const_iterator it = e.begin();
-  VectorValues y = zero();
-  for(auto& key_value: y) {
-    key_value.second = *it;
-    ++it;
-  }
-  transposeMultiplyAdd2(1.0, it, e.end(), y);
-  return y;
-}
-
 /* ************************************************************************* */
 // y += alpha*A'*e
 void SubgraphPreconditioner::transposeMultiplyAdd
diff --git a/gtsam/linear/SubgraphPreconditioner.h b/gtsam/linear/SubgraphPreconditioner.h
index 558a80bd8..9e005dd53 100644
--- a/gtsam/linear/SubgraphPreconditioner.h
+++ b/gtsam/linear/SubgraphPreconditioner.h
@@ -125,9 +125,6 @@ namespace gtsam {
     /** Apply operator A in place: needs e allocated already */
     void multiplyInPlace(const VectorValues& y, Errors& e) const;
 
-    /** Apply operator A' */
-    VectorValues operator^(const Errors& e) const;
-
     /**
     * Add A'*e to y
     *  y += alpha*A'*[e1;e2] = [alpha*e1; alpha*inv(R1')*A2'*e2]
diff --git a/gtsam/linear/iterative.h b/gtsam/linear/iterative.h
index 22f65b8de..ff3d73801 100644
--- a/gtsam/linear/iterative.h
+++ b/gtsam/linear/iterative.h
@@ -59,11 +59,6 @@ namespace gtsam {
     /** Access b vector */
     const Vector& b() const { return b_; }
 
-    /** Apply operator A'*e */
-    Vector operator^(const Vector& e) const {
-      return A_ ^ e;
-    }
-
     /**
      * Print with optional string
      */
@@ -71,7 +66,7 @@ namespace gtsam {
 
     /** gradient of objective function 0.5*|Ax-b_|^2 at x = A_'*(Ax-b_) */
     Vector gradient(const Vector& x) const {
-      return A() ^ (A() * x - b());
+      return A().transpose() * (A() * x - b());
     }
 
     /** Apply operator A */