diff --git a/preamble_formulas.sty b/preamble_formulas.sty
index c7ac005..76afd53 100644
--- a/preamble_formulas.sty
+++ b/preamble_formulas.sty
@@ -99,6 +99,7 @@
       {INLP}{\phy}  % Instabilities and nonlinear phenomena
       {MM}{\sta}    % Montecarlo methods
       {CO}{\apl}    % Continuous optimization
+      {NMPDE}{\apl} % Numerical methods for pdes
   }{\col}%
 }
 \ExplSyntaxOff