Prevent lower IRLS start chi than target chi

Author: domfournier

simpeg_drivers/components/factories/directives_factory.py

@@ -15,6 +15,7 @@
 from __future__ import annotations
 
 from abc import ABC
+from logging import getLogger
 from typing import TYPE_CHECKING
 
 import numpy as np
@@ -29,6 +30,8 @@
 if TYPE_CHECKING:
     from simpeg_drivers.driver import InversionDriver
 
+logger = getLogger(__name__)
+
 
 class DirectivesFactory:
     def __init__(self, driver: InversionDriver):
@@ -263,7 +266,15 @@ def scale_misfits(self):
     def update_irls_directive(self):
         """Directive to update IRLS."""
         if self._update_irls_directive is None:
-            has_chi_start = self.params.starting_chi_factor is not None
+            start_chi_fact = self.params.starting_chi_factor
+
+            if start_chi_fact is not None and self.params.chi_factor > start_chi_fact:
+                logger.warning(
+                    "Starting chi factor is greater than target chi factor.\n"
+                    "Setting the target chi factor to the starting chi factor."
+                )
+                start_chi_fact = self.params.chi_factor
+
             self._update_irls_directive = directives.UpdateIRLS(
                 f_min_change=self.params.f_min_change,
                 max_irls_iterations=self.params.max_irls_iterations,
@@ -272,11 +283,7 @@ def update_irls_directive(self):
                 cooling_rate=self.params.cooling_rate,
                 cooling_factor=self.params.cooling_factor,
                 irls_cooling_factor=self.params.epsilon_cooling_factor,
-                chifact_start=(
-                    self.params.starting_chi_factor
-                    if has_chi_start
-                    else self.params.chi_factor
-                ),
+                chifact_start=start_chi_fact or self.params.chi_factor,
                 chifact_target=self.params.chi_factor,
             )
         return self._update_irls_directive