From 97d174722301dfff89b32d1205a8a4332f7ecf24 Mon Sep 17 00:00:00 2001
From: unalmis <kayaunalmis@proton.me>
Date: Wed, 18 Sep 2024 19:45:31 -0400
Subject: [PATCH] Add negative sign to residual for diagbroyden optimizer

---
 desc/equilibrium/coords.py      | 6 +++---
 desc/equilibrium/equilibrium.py | 1 -
 desc/vmec.py                    | 8 ++------
 3 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/desc/equilibrium/coords.py b/desc/equilibrium/coords.py
index 6e941a2e5..8a02e5eaa 100644
--- a/desc/equilibrium/coords.py
+++ b/desc/equilibrium/coords.py
@@ -134,7 +134,7 @@ def map_coordinates(  # noqa: C901
                 L_lmn=params["L_lmn"],
                 L_basis=eq.L_basis,
                 guess=guess[:, 1] if guess is not None else None,
-                period=period[1] if period is not None else 2 * np.pi,
+                period=period[1] if period is not None else np.inf,
                 tol=tol,
                 maxiter=maxiter,
                 full_output=full_output,
@@ -289,7 +289,7 @@ def _map_PEST_coordinates(
     L_lmn,
     L_basis,
     guess,
-    period=2 * np.pi,
+    period=np.inf,
     tol=1e-6,
     maxiter=30,
     full_output=False,
@@ -311,7 +311,7 @@ def _map_PEST_coordinates(
         Shape (k, ).
         Optional initial guess for the computational coordinates.
     period : float
-        Assumed periodicity for ϑ. Default is 2π.
+        Assumed periodicity for ϑ.
         Use ``np.inf`` to denote no periodicity.
     tol : float
         Stopping tolerance.
diff --git a/desc/equilibrium/equilibrium.py b/desc/equilibrium/equilibrium.py
index 4e0ea1588..dd85b123c 100644
--- a/desc/equilibrium/equilibrium.py
+++ b/desc/equilibrium/equilibrium.py
@@ -1266,7 +1266,6 @@ def compute_theta_coords(
             inbasis=("rho", "theta_PEST", "zeta"),
             outbasis=("rho", "theta", "zeta"),
             params=self.params_dict if L_lmn is None else {"L_lmn": L_lmn},
-            period=(np.inf, 2 * np.pi, np.inf),
             tol=tol,
             maxiter=maxiter,
             full_output=full_output,
diff --git a/desc/vmec.py b/desc/vmec.py
index 972d5248a..904fd8f2d 100644
--- a/desc/vmec.py
+++ b/desc/vmec.py
@@ -1722,7 +1722,7 @@ def root_fun(theta):
             )
             theta_PEST_k = theta + lmbda
             r = theta_PEST_k - theta_PEST
-            return r
+            return -r  # the negative sign is necessary
 
         out = optimize.root(
             root_fun, x0=theta_PEST, method="diagbroyden", options={"ftol": 1e-6}
@@ -1786,11 +1786,7 @@ def compute_coord_surfaces(cls, equil, vmec_data, Nr=10, Nt=8, Nz=None, **kwargs
 
         # find theta angles corresponding to desired theta* angles
         v_grid = Grid(
-            equil.map_coordinates(
-                t_grid.nodes,
-                inbasis=("rho", "theta_PEST", "zeta"),
-                period=(np.inf, 2 * np.pi, np.inf),
-            )
+            equil.map_coordinates(t_grid.nodes, inbasis=("rho", "theta_PEST", "zeta"))
         )
         r_coords_desc = equil.compute(["R", "Z"], grid=r_grid)
         v_coords_desc = equil.compute(["R", "Z"], grid=v_grid)