diff --git a/src/utilities/is/isfreq.m b/src/utilities/is/isfreq.m
index 79ba42c5395ab9484bff5e18f10a69ffb37b79d0..f552bdca81e10f4e3686aae5fb433aea0a70699c 100644
--- a/src/utilities/is/isfreq.m
+++ b/src/utilities/is/isfreq.m
@@ -25,15 +25,15 @@ function B = isfreq(A)
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-B = 0;
+B = false;
 
 if ischar(A)
     if isequal(length(A),1) && ismember(upper(A),{'Y','A','Q','M','W'})
-        B = 1;
+        B = true;
         return
     end
 end
 
 if isnumeric(A) && isequal(length(A),1) && ismember(A,[1 4 12 52])
-    B = 1;
+    B = true;
 end
\ No newline at end of file
diff --git a/src/utilities/is/ismonthly.m b/src/utilities/is/ismonthly.m
index b722b359fde07dddb097413c6f6cbc8d12879db0..bdf7e2460803db4f9df7fe53ebe6450455a57aa4 100644
--- a/src/utilities/is/ismonthly.m
+++ b/src/utilities/is/ismonthly.m
@@ -27,12 +27,12 @@ function b = ismonthly(str)  % --*-- Unitary tests --*--
 
 if ischar(str)
     if isempty(regexp(str,'^-?[0-9]*[Mm]([1-9]|1[0-2])$','once'))
-        b = 0;
+        b = false;
     else
-        b = 1;
+        b = true;
     end
 else
-    b = 0;
+    b = false;
 end
 
 %@test:1
@@ -46,13 +46,13 @@ end
 %$ date_7 = '1950Q3';
 %$ date_8 = '1950m24';
 %$
-%$ t(1) = dassert(ismonthly(date_1),1);
-%$ t(2) = dassert(ismonthly(date_2),1);
-%$ t(3) = dassert(ismonthly(date_3),1);
-%$ t(4) = dassert(ismonthly(date_4),1);
-%$ t(5) = dassert(ismonthly(date_5),0);
-%$ t(6) = dassert(ismonthly(date_6),0);
-%$ t(7) = dassert(ismonthly(date_7),0);
-%$ t(8) = dassert(ismonthly(date_8),0);
+%$ t(1) = dassert(ismonthly(date_1),true);
+%$ t(2) = dassert(ismonthly(date_2),true);
+%$ t(3) = dassert(ismonthly(date_3),true);
+%$ t(4) = dassert(ismonthly(date_4),true);
+%$ t(5) = dassert(ismonthly(date_5),false);
+%$ t(6) = dassert(ismonthly(date_6),false);
+%$ t(7) = dassert(ismonthly(date_7),false);
+%$ t(8) = dassert(ismonthly(date_8),false);
 %$ T = all(t);
 %@eof:1
\ No newline at end of file
diff --git a/src/utilities/is/isquaterly.m b/src/utilities/is/isquaterly.m
index d8d8146716cf67e9ba54b2d76d07a4bc15fdb459..8171ca35c05ab08fdaac7021a3687ea52e849cca 100644
--- a/src/utilities/is/isquaterly.m
+++ b/src/utilities/is/isquaterly.m
@@ -27,12 +27,12 @@ function b = isquaterly(str)  % --*-- Unitary tests --*--
 
 if ischar(str)
     if isempty(regexp(str,'^-?[0-9]*[Qq][1-4]$','once'))
-        b = 0;
+        b = false;
     else
-        b = 1;
+        b = true;
     end
 else
-    b = 0;
+    b = false;
 end
 
 %@test:1
@@ -45,12 +45,12 @@ end
 %$ date_6 = '1950Y';
 %$ date_7 = '1950m24';
 %$
-%$ t(1) = dassert(isquaterly(date_1),1);
-%$ t(2) = dassert(isquaterly(date_2),1);
-%$ t(3) = dassert(isquaterly(date_3),1);
-%$ t(4) = dassert(isquaterly(date_4),0);
-%$ t(5) = dassert(isquaterly(date_5),0);
-%$ t(6) = dassert(isquaterly(date_6),0);
-%$ t(7) = dassert(isquaterly(date_7),0);
+%$ t(1) = dassert(isquaterly(date_1),true);
+%$ t(2) = dassert(isquaterly(date_2),true);
+%$ t(3) = dassert(isquaterly(date_3),true);
+%$ t(4) = dassert(isquaterly(date_4),false);
+%$ t(5) = dassert(isquaterly(date_5),false);
+%$ t(6) = dassert(isquaterly(date_6),false);
+%$ t(7) = dassert(isquaterly(date_7),false);
 %$ T = all(t);
 %@eof:1
\ No newline at end of file
diff --git a/src/utilities/is/isstringdate.m b/src/utilities/is/isstringdate.m
index d9c6d5e7cb41a409de1e30c4b448c7e8d000d82c..56fe59cfd4e782d80aef83337e6fbfa031d33654 100644
--- a/src/utilities/is/isstringdate.m
+++ b/src/utilities/is/isstringdate.m
@@ -28,7 +28,7 @@ function b = isstringdate(str)  % --*-- Unitary tests --*--
 if ischar(str)
     b = isquaterly(str) || isyearly(str) || ismonthly(str) || isweekly(str);
 else
-    b = 0;
+    b = false;
 end
 
 %@test:1
diff --git a/src/utilities/is/isweekly.m b/src/utilities/is/isweekly.m
index b7fbe934af3ea3befc8a2ab218f8074c5c93f8bf..4cdd20085730946ef5108a6d02c0fc91097e95a3 100644
--- a/src/utilities/is/isweekly.m
+++ b/src/utilities/is/isweekly.m
@@ -27,12 +27,12 @@ function b = isweekly(str)  % --*-- Unitary tests --*--
 
 if ischar(str)
     if isempty(regexp(str,'^-?[0-9]*[Ww]([1-9]|[1-4][0-9]|5[0-2])$','once'))
-        b = 0;
+        b = false;
     else
-        b = 1;
+        b = true;
     end
 else
-    b = 0;
+    b = false;
 end
 
 %@test:1
@@ -41,18 +41,18 @@ end
 %$ date_2 = '1950w2';
 %$ date_3 = '-1950w2';
 %$ date_4 = '1950w22';
-%$ date_5 = '1950 azd ';
+%$ date_5 = '1950 azd';
 %$ date_6 = '1950Y';
 %$ date_7 = '1950Q3';
 %$ date_8 = '1950m54';
 %$
-%$ t(1) = dassert(isweekly(date_1),1);
-%$ t(2) = dassert(isweekly(date_2),1);
-%$ t(3) = dassert(isweekly(date_3),1);
-%$ t(4) = dassert(isweekly(date_4),1);
-%$ t(5) = dassert(isweekly(date_5),0);
-%$ t(6) = dassert(isweekly(date_6),0);
-%$ t(7) = dassert(isweekly(date_7),0);
-%$ t(8) = dassert(isweekly(date_8),0);
+%$ t(1) = dassert(isweekly(date_1),true);
+%$ t(2) = dassert(isweekly(date_2),true);
+%$ t(3) = dassert(isweekly(date_3),true);
+%$ t(4) = dassert(isweekly(date_4),true);
+%$ t(5) = dassert(isweekly(date_5),false);
+%$ t(6) = dassert(isweekly(date_6),false);
+%$ t(7) = dassert(isweekly(date_7),false);
+%$ t(8) = dassert(isweekly(date_8),false);
 %$ T = all(t);
 %@eof:1
\ No newline at end of file
diff --git a/src/utilities/is/isyearly.m b/src/utilities/is/isyearly.m
index bf8c03568a6666c9e62118c509bf1e55142659fd..79508650a163bef751a5c938b22120eab87b135a 100644
--- a/src/utilities/is/isyearly.m
+++ b/src/utilities/is/isyearly.m
@@ -27,12 +27,12 @@ function b = isyearly(str)  % --*-- Unitary tests --*--
 
 if ischar(str)
     if isempty(regexp(str,'^-?[0-9]*[YyAa]$','once'))
-        b = 0;
+        b = false;
     else
-        b = 1;
+        b = true;
     end
 else
-    b = 0;
+    b = false;
 end
 
 %@test:1
@@ -46,13 +46,13 @@ end
 %$ date_7 = '-1950a';
 %$ date_8 = '1950m24';
 %$
-%$ t(1) = dassert(isyearly(date_1),0);
-%$ t(2) = dassert(isyearly(date_2),0);
-%$ t(3) = dassert(isyearly(date_3),0);
-%$ t(4) = dassert(isyearly(date_4),0);
-%$ t(5) = dassert(isyearly(date_5),0);
-%$ t(6) = dassert(isyearly(date_6),1);
-%$ t(7) = dassert(isyearly(date_7),1);
-%$ t(8) = dassert(isyearly(date_8),0);
+%$ t(1) = dassert(isyearly(date_1),false);
+%$ t(2) = dassert(isyearly(date_2),false);
+%$ t(3) = dassert(isyearly(date_3),false);
+%$ t(4) = dassert(isyearly(date_4),false);
+%$ t(5) = dassert(isyearly(date_5),false);
+%$ t(6) = dassert(isyearly(date_6),true);
+%$ t(7) = dassert(isyearly(date_7),true);
+%$ t(8) = dassert(isyearly(date_8),false);
 %$ T = all(t);
 %@eof:1
\ No newline at end of file