Merge branch 'fix_nullop_stat_ncg' into 'NIFTy_8'

_static_newton_cg: Fix maxiter==0 handling

Closes #426

See merge request !1009

src/re/optimize.py

@@ -327,8 +327,8 @@ def _static_newton_cg(
     energy, g = fun_and_grad(pos)
     conditional_raise(jnp.isnan(energy), ValueError("energy is Nan"))
     val = {
-        "status": -2,
-        "iteration": 1,
+        "status": jnp.where(maxiter == 0, 0, -2),
+        "iteration": 0,
         "pos": pos,
         "energy": energy,
         "old_energy": old_fval if old_fval is not None else jnp.inf,
@@ -342,7 +342,7 @@ def _static_newton_cg(
         return v["status"] < -1
 
     def single_newton_cg_step(v):
-        status, i = v["status"], v["iteration"]
+        status, i = v["status"], v["iteration"] + 1
         pos = v["pos"]
         energy, g = v["energy"], v["g"]
         old_energy = v["old_energy"]
@@ -419,7 +419,7 @@ def _static_newton_cg(
 
         ret = {
             "status": status,
-            "iteration": i + 1,
+            "iteration": i,
             "pos": pos,
             "energy": energy,
             "old_energy": old_energy,
@@ -432,7 +432,9 @@ def _static_newton_cg(
 
     val = while_loop(continue_condition_newton_cg, single_newton_cg_step, val)
     conditional_call(
-        val["status"] > 0, logger.error, PyTreeString(f"{nm}: Iteration Limit Reached!")
+        (val["status"] > 0) | (maxiter == 0),
+        logger.error,
+        PyTreeString(f"{nm}: Iteration Limit Reached!"),
     )
     return OptimizeResults(
         x=val["pos"],