diff --git a/fortran/bobyqa/geometry.f90 b/fortran/bobyqa/geometry.f90
index 2cd792b7f8..14c2324ab9 100644
--- a/fortran/bobyqa/geometry.f90
+++ b/fortran/bobyqa/geometry.f90
@@ -8,7 +8,7 @@ module geometry_bobyqa_mod
 !
 ! Started: February 2022
 !
-! Last Modified: Sunday, April 21, 2024 PM01:57:17
+! Last Modified: Sunday, April 21, 2024 PM03:19:27
 !--------------------------------------------------------------------------------------------------!
 
 implicit none
@@ -41,7 +41,7 @@ function setdrop_tr(kopt, ximproved, bmat, d, delta, rho, xpt, zmat) result(knew
 use, non_intrinsic :: consts_mod, only : RP, IK, ONE, DEBUGGING
 use, non_intrinsic :: debug_mod, only : assert
 use, non_intrinsic :: infnan_mod, only : is_nan, is_finite
-use, non_intrinsic :: linalg_mod, only : issymmetric
+use, non_intrinsic :: linalg_mod, only : issymmetric, trueloc
 use, non_intrinsic :: powalg_mod, only : calden
 
 implicit none
@@ -139,14 +139,15 @@ function setdrop_tr(kopt, ximproved, bmat, d, delta, rho, xpt, zmat) result(knew
     score(kopt) = -ONE
 end if
 
+! SCORE(K) = NaN implies DEN(K) = NaN. We exclude such K as we want DEN to be big.
+score(trueloc(is_nan(score))) = -ONE
+
 knew = 0
-! The following IF works slightly better than `IF (ANY(SCORE > 0))` from Powell's BOBYQA and LINCOA
-! code.
+! The following IF works slightly better than `IF (ANY(SCORE > 0))` from Powell's BOBYQA/LINCOA code.
 if (any(score > 1) .or. (ximproved .and. any(score > 0))) then  ! Powell's UOBYQA and NEWUOA code.
     ! See (6.1) of the BOBYQA paper for the definition of KNEW in this case.
-    ! SCORE(K) = NaN implies DEN(K) = NaN. We exclude such K as we want DEN to be big.
-    knew = int(maxloc(score, mask=(.not. is_nan(score)), dim=1), kind(knew))
-    !!MATLAB: [~, knew] = max(score, [], 'omitnan');
+    knew = int(maxloc(score, dim=1), kind(knew))
+    !!MATLAB: [~, knew] = max(score);
 end if
 
 ! Powell's code does not include the following instructions. With Powell's code, if DEN consists of
diff --git a/fortran/cobyla/geometry.f90 b/fortran/cobyla/geometry.f90
index 0a53a672ba..8d95b0b861 100644
--- a/fortran/cobyla/geometry.f90
+++ b/fortran/cobyla/geometry.f90
@@ -8,7 +8,7 @@ module geometry_cobyla_mod
 !
 ! Started: July 2021
 !
-! Last Modified: Sunday, April 21, 2024 PM01:57:52
+! Last Modified: Sunday, April 21, 2024 PM03:16:37
 !--------------------------------------------------------------------------------------------------!
 
 implicit none
@@ -32,7 +32,7 @@ function setdrop_tr(ximproved, d, delta, rho, sim, simi) result(jdrop)
 
 ! Common modules
 use, non_intrinsic :: consts_mod, only : IK, RP, ZERO, ONE, TENTH, DEBUGGING
-use, non_intrinsic :: linalg_mod, only : matprod, isinv
+use, non_intrinsic :: linalg_mod, only : matprod, isinv, trueloc
 use, non_intrinsic :: infnan_mod, only : is_nan, is_finite
 use, non_intrinsic :: debug_mod, only : assert
 
@@ -168,12 +168,14 @@ function setdrop_tr(ximproved, d, delta, rho, sim, simi) result(jdrop)
     score(n + 1) = -ONE
 end if
 
+score(trueloc(is_nan(score))) = -ONE
+
 jdrop = 0
 ! The following IF works a bit better than `IF (ANY(SCORE > 1) .OR. ANY(SCORE > 0) .AND. XIMPROVED)`
 ! from Powell's UOBYQA and NEWUOA code.
 if (any(score > 0)) then  ! Powell's BOBYQA and LINCOA code
-    jdrop = int(maxloc(score, mask=(.not. is_nan(score)), dim=1), kind(jdrop))
-    !!MATLAB: [~, jdrop] = max(score, [], 'omitnan');
+    jdrop = int(maxloc(score, dim=1), kind(jdrop))
+    !!MATLAB: [~, jdrop] = max(score);
 end if
 
 if ((ximproved .and. jdrop == 0) .or. jdrop < 0) then  ! JDROP < 0 is impossible in theory.
diff --git a/fortran/lincoa/geometry.f90 b/fortran/lincoa/geometry.f90
index afdbb019c7..b01613afb9 100644
--- a/fortran/lincoa/geometry.f90
+++ b/fortran/lincoa/geometry.f90
@@ -8,7 +8,7 @@ module geometry_lincoa_mod
 !
 ! Started: February 2022
 !
-! Last Modified: Sunday, April 21, 2024 PM01:54:26
+! Last Modified: Sunday, April 21, 2024 PM03:15:36
 !--------------------------------------------------------------------------------------------------!
 
 implicit none
@@ -38,7 +38,7 @@ function setdrop_tr(idz, kopt, ximproved, bmat, d, delta, rho, xpt, zmat) result
 use, non_intrinsic :: consts_mod, only : RP, IK, ONE, TENTH, DEBUGGING
 use, non_intrinsic :: debug_mod, only : assert
 use, non_intrinsic :: infnan_mod, only : is_nan, is_finite
-use, non_intrinsic :: linalg_mod, only : issymmetric
+use, non_intrinsic :: linalg_mod, only : issymmetric, trueloc
 use, non_intrinsic :: powalg_mod, only : calden
 
 implicit none
@@ -160,13 +160,15 @@ function setdrop_tr(idz, kopt, ximproved, bmat, d, delta, rho, xpt, zmat) result
     score(kopt) = -ONE
 end if
 
+! SCORE(K) is NaN implies ABS(DEN(K)) is NaN, but we want ABS(DEN) to be big. So we exclude such K.
+score(trueloc(is_nan(score))) = -ONE
+
 knew = 0
 ! The following IF works a bit better than `IF (ANY(SCORE > 1) .OR. ANY(SCORE > 0) .AND. XIMPROVED)`
 ! from Powell's UOBYQA and NEWUOA code.
 if (any(score > 0)) then  ! Powell's BOBYQA and LINCOA code
-    ! SCORE(K) is NaN implies ABS(DEN(K)) is NaN, but we want ABS(DEN) to be big. So we exclude such K.
-    knew = int(maxloc(score, mask=(.not. is_nan(score)), dim=1), kind(knew))
-    !!MATLAB: [~, knew] = max(score, [], 'omitnan');
+    knew = int(maxloc(score, dim=1), kind(knew))
+    !!MATLAB: [~, knew] = max(score);
 end if
 
 ! Powell's code does not include the following instructions. With Powell's code, if DEN consists of
diff --git a/fortran/newuoa/geometry.f90 b/fortran/newuoa/geometry.f90
index 42b0c0c340..de89c353e5 100644
--- a/fortran/newuoa/geometry.f90
+++ b/fortran/newuoa/geometry.f90
@@ -8,7 +8,7 @@ module geometry_newuoa_mod
 !
 ! Started: July 2020
 !
-! Last Modified: Sunday, April 21, 2024 PM02:47:22
+! Last Modified: Sunday, April 21, 2024 PM03:20:57
 !--------------------------------------------------------------------------------------------------!
 
 implicit none
@@ -40,7 +40,7 @@ function setdrop_tr(idz, kopt, ximproved, bmat, d, delta, rho, xpt, zmat) result
 use, non_intrinsic :: consts_mod, only : RP, IK, ONE, TENTH, DEBUGGING
 use, non_intrinsic :: debug_mod, only : assert
 use, non_intrinsic :: infnan_mod, only : is_nan, is_finite
-use, non_intrinsic :: linalg_mod, only : issymmetric
+use, non_intrinsic :: linalg_mod, only : issymmetric, trueloc
 use, non_intrinsic :: powalg_mod, only : calden
 
 implicit none
@@ -128,13 +128,15 @@ function setdrop_tr(idz, kopt, ximproved, bmat, d, delta, rho, xpt, zmat) result
     score(kopt) = -ONE
 end if
 
+! SCORE(K) is NaN implies ABS(DEN(K)) is NaN, but we want ABS(DEN) to be big. So we exclude such K.
+score(trueloc(is_nan(score))) = -ONE
+
 knew = 0
-! The following IF works a bit better than `IF (ANY(SCORE > 0))` from Powell's BOBYQA and LINCOA code.
+! The following IF works a bit better than `IF (ANY(SCORE > 0))` from Powell's BOBYQA/LINCOA code.
 if (any(score > 1) .or. (ximproved .and. any(score > 0))) then  ! Powell's UOBYQA and NEWUOA code
     ! See (7.5) of the NEWUOA paper for the definition of KNEW in this case.
-    ! SCORE(K) is NaN implies ABS(DEN(K)) is NaN, but we want ABS(DEN) to be big. So we exclude such K.
-    knew = int(maxloc(score, mask=(.not. is_nan(score)), dim=1), kind(knew))
-    !!MATLAB: [~, knew] = max(score, [], 'omitnan');
+    knew = int(maxloc(score, dim=1), kind(knew))
+    !!MATLAB: [~, knew] = max(score);
 end if
 
 ! Powell's code does not include the following instructions. With Powell's code, if DEN consists of
diff --git a/fortran/uobyqa/geometry.f90 b/fortran/uobyqa/geometry.f90
index 1a9a5a95cd..51e541fd4d 100644
--- a/fortran/uobyqa/geometry.f90
+++ b/fortran/uobyqa/geometry.f90
@@ -8,7 +8,7 @@ module geometry_uobyqa_mod
 !
 ! Started: February 2022
 !
-! Last Modified: Sunday, April 21, 2024 PM01:52:04
+! Last Modified: Sunday, April 21, 2024 PM03:17:27
 !--------------------------------------------------------------------------------------------------!
 
 implicit none
@@ -41,6 +41,7 @@ function setdrop_tr(kopt, ximproved, d, pl, rho, xpt) result(knew)
 use, non_intrinsic :: consts_mod, only : RP, IK, ONE, DEBUGGING
 use, non_intrinsic :: debug_mod, only : assert
 use, non_intrinsic :: infnan_mod, only : is_nan, is_finite
+use, non_intrinsic :: linalg_mod, only : trueloc
 use, non_intrinsic :: powalg_mod, only : calvlag
 
 implicit none
@@ -132,13 +133,15 @@ function setdrop_tr(kopt, ximproved, d, pl, rho, xpt) result(knew)
     score(kopt) = -ONE
 end if
 
+! SCORE(K) is NaN implies VLAG(K) is NaN, but we want ABS(VLAG) to be big. So we exclude such K.
+score(trueloc(is_nan(score))) = -ONE
+
 knew = 0
 ! It makes almost no difference if we change the IF below to `IF (ANY(SCORE>0))`, which is used
 ! in Powell's BOBYQA and LINCOA code.
 if (any(score > 1) .or. (ximproved .and. any(score > 0))) then  ! Powell's UOBYQA and NEWUOA code
-    ! SCORE(K) is NaN implies VLAG(K) is NaN, but we want ABS(VLAG) to be big. So we exclude such K.
-    knew = int(maxloc(score, mask=(.not. is_nan(score)), dim=1), kind(knew))
-    !!MATLAB: [~, knew] = max(score, [], 'omitnan');
+    knew = int(maxloc(score, dim=1), kind(knew))
+    !!MATLAB: [~, knew] = max(score);
 end if
 
 ! Powell's code does not include the following instructions. With Powell's code, if VLAG consists of