initial commit of Gregorian/IFC date conversion tools and unit tests

DAYSOFWEEK.m

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+classdef DAYSOFWEEK < uint8
+    enumeration
+        Saturday (0), Sunday (1), Monday (2), Tuesday (3), Wednesday (4), Thursday (5), Friday (6), YearDay (7), LeapDay (8)
+    end
+end

IFC.m

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+function fixed = IFC(gregorian)
+arguments (Input)
+    gregorian (:,1) datetime
+end
+arguments (Output)
+    fixed (:, 4) table
+end
+% gregorian datetime 1 arg input?
+% y/m/d 3 args input?
+% TODO inputs validation
+
+% prepare output struct
+fixed = struct('Year', [], 'Month', '', 'Day', [], 'DayOfWeek', '');
+fixed = repmat(fixed, length(gregorian), 1);
+
+% eliminate time from input, only date matters
+gregorian.Hour = 0; gregorian.Minute = 0; gregorian.Second = 0;
+
+% year remains constant
+Year = num2cell(uint16(year(gregorian')));
+[fixed.Year] = Year{:};
+
+% find number of days into the current year
+Days = days(gregorian - datetime([fixed.Year] - 1, 12, 31)');
+
+% Calculate IFC month, number of days into that month, and if leap day
+% and/or year day occured
+[nMonths, nDays, leaped, yeared] = IFCmonths(Days, [fixed.Year]');
+
+% write month to output
+Month = num2cell(MONTHS(nMonths));
+[fixed.Month] = Month{:};
+
+% write number of days in month to output
+nDays = num2cell(nDays);
+[fixed.Day] = nDays{:};
+
+% write day of week to output
+DOW = num2cell(DAYSOFWEEK(mod([fixed.Day]', 7)));
+[fixed.DayOfWeek] = DOW{:};
+
+% Write year days as special days of the week
+yearDays = num2cell(repmat(DAYSOFWEEK(7), 1, sum(yeared)));
+[fixed(yeared).DayOfWeek] = yearDays{:}; % try 2 year/leap days in a vector input
+
+% Write leap days as special days of the week
+leapDayFlags = ~yeared & leaped & [fixed.Month]' == MONTHS(14) & [fixed.Day]' == 0; 
+leapDays = num2cell(repmat(DAYSOFWEEK(8), 1, sum(leapDayFlags)));
+[fixed(leapDayFlags).DayOfWeek] = leapDays{:};
+
+% convert output to table
+fixed = struct2table(fixed);
+end

IFCmonths.m

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+function [nMonths, Days, leaped, yeared] = IFCmonths(Days, Year)
+arguments (Input)
+    Days    (:, 1) uint16
+    Year    (:, 1) uint16
+end
+arguments (Output)
+    nMonths (:, 1) uint8
+    Days    (:, 1) uint8
+    leaped  (:, 1) logical
+    yeared  (:, 1) logical
+end
+
+% intialize output to first month
+nMonths = ones(size(Days));
+
+% initialize output saying a leap day happened to false
+leaped = false(size(Days));
+
+% initialize output saying a year day happened to false
+yeared = false(size(Days));
+
+% check if it's a leap year
+leap = isLeap(Year);
+
+% while more days than 1 month, add months to nMonths
+excess = Days > 28;
+while any(excess)
+    % Subtract 28 days and add one month
+    Days(excess) = Days(excess) - 28;
+    nMonths(excess) = nMonths(excess) + 1;
+
+    % Find dates which are reaching the leap day (if it exists)
+    leaping = (leap & nMonths == 7);
+    % subtract leap day before proceeding to add another month
+    Days(leaping) = Days(leaping) - 1;
+    % Set leap day output to true
+    leaped(leaping) = true;
+    % Set the month to 14 (no month) if there are no days left
+    % meaning the last day is the leap day 
+    % (which is not in any month)
+    noneLeft = ~Days;
+    nMonths(noneLeft) = 14;
+    % continue subtracting days and adding months as needed
+
+    % find excess days remaining for next iteration
+    excess = Days > 28;
+end
+
+% check for if a year day occured
+yearing = (nMonths == 14 & Days == 1);
+yeared(yearing) = true; % Year day achieved, set flag
+Days(yearing) = 0; % decrement Days since year day was taken
+end

MONTHS.m

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+classdef MONTHS < uint8
+    enumeration
+        January (1), February (2), March (3), April (4), May (5), June (6), Sol (7), July (8), August (9), September (10), October (11), November (12), December (13), None (14)
+    end
+end

isLeap.m

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+function flag = isLeap(Year)
+arguments (Input)
+    Year (:, 1) uint16
+end
+arguments (Output)
+    flag (:, 1) logical
+end
+
+% flag = NaN(size(Year));
+
+isDivisibleBy4 = ~mod(Year, 4);
+isNotDivisibleBy100 = logical(mod(Year, 100));
+isDivisibleBy400 = ~mod(Year, 400);
+
+flag = isDivisibleBy4 & (isDivisibleBy400 | isNotDivisibleBy100);
+
+% if ~mod(Year, 4)
+%     if ~mod(Year, 100) 
+%         if ~mod(Year, 400)
+%             flag = true;
+%         else
+%             flag = false;
+%         end
+%     else
+%         flag = true;
+%     end
+% else
+%     flag = false;
+% end
+end

test_IFC.m

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+classdef test_IFC < matlab.unittest.TestCase
+    
+    methods(TestClassSetup)
+        % Shared setup for the entire test class
+    end
+    
+    methods(TestMethodSetup)
+        % Setup for each test
+    end
+    
+    methods(Test)
+        % Test methods
+        
+        function test_today(testCase)
+            ifc = IFC(datetime('28-Dec-2024'));
+            testCase.verifyEqual(ifc.Year, uint16(2024));
+            testCase.verifyEqual(ifc.Month, MONTHS(13));
+            testCase.verifyEqual(ifc.Day, uint8(26));
+            testCase.verifyEqual(ifc.DayOfWeek, DAYSOFWEEK(5));
+        end
+
+        function test_yearday_noleap(testCase)
+            ifc = IFC(datetime('31-Dec-2023'));
+            testCase.verifyEqual(ifc.Year, uint16(2023));
+            testCase.verifyEqual(ifc.Month, MONTHS(14));
+            testCase.verifyEqual(ifc.Day, uint8(0));
+            testCase.verifyEqual(ifc.DayOfWeek, DAYSOFWEEK(7));
+        end
+
+        function test_yearday_leap(testCase)
+            ifc = IFC(datetime('31-Dec-2020'));
+            testCase.verifyEqual(ifc.Year, uint16(2020));
+            testCase.verifyEqual(ifc.Month, MONTHS(14));
+            testCase.verifyEqual(ifc.Day, uint8(0));
+            testCase.verifyEqual(ifc.DayOfWeek, DAYSOFWEEK(7));
+        end
+
+        function test_leapday_noleap(testCase)
+            ifc = IFC(datetime('17-Jun-2003'));
+            testCase.verifyEqual(ifc.Year, uint16(2003));
+            testCase.verifyEqual(ifc.Month, MONTHS(6));
+            testCase.verifyEqual(ifc.Day, uint8(28));
+            testCase.verifyEqual(ifc.DayOfWeek, DAYSOFWEEK(0));
+        end
+
+        function test_leapday_leap(testCase)
+            ifc = IFC(datetime('17-Jun-2008'));
+            testCase.verifyEqual(ifc.Year, uint16(2008));
+            testCase.verifyEqual(ifc.Month, MONTHS(14));
+            testCase.verifyEqual(ifc.Day, uint8(0));
+            testCase.verifyEqual(ifc.DayOfWeek, DAYSOFWEEK(8));
+        end
+
+        function test_all_vectorized(testCase)
+            ifc = IFC(datetime(["28-Dec-2024"; "31-Dec-2023"; "31-Dec-2020"; "17-Jun-2003"; "17-Jun-2008"]));
+            testCase.verifyEqual([ifc.Year], uint16([2024; 2023; 2020; 2003; 2008]));
+            testCase.verifyEqual([ifc.Month], MONTHS([13; 14; 14; 6; 14]));
+            testCase.verifyEqual([ifc.Day], uint8([26; 0; 0; 28; 0]));
+            testCase.verifyEqual([ifc.DayOfWeek], DAYSOFWEEK([5; 7; 7; 0; 8]));
+        end
+    end
+    
+end

test_IFCmonths.m

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+classdef test_IFCmonths < matlab.unittest.TestCase
+    
+    methods(TestClassSetup)
+        % Shared setup for the entire test class
+    end
+    
+    methods(TestMethodSetup)
+        % Setup for each test
+    end
+    
+    methods(Test)
+        % Test methods
+        
+        function test_jan1(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(1, 2000);
+            testCase.verifyEqual(nMonths, uint8(1));
+            testCase.verifyEqual(nDays, uint8(1));
+            testCase.verifyFalse(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_jan31(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(31, 2000);
+            testCase.verifyEqual(nMonths, uint8(2));
+            testCase.verifyEqual(nDays, uint8(3));
+            testCase.verifyFalse(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_jun17_leap(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(168, 2000);
+            testCase.verifyEqual(nMonths, uint8(6));
+            testCase.verifyEqual(nDays, uint8(28));
+            testCase.verifyFalse(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_jun17_noleap(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(168, 2001);
+            testCase.verifyEqual(nMonths, uint8(6));
+            testCase.verifyEqual(nDays, uint8(28));
+            testCase.verifyFalse(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_jun18_leap(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(169, 2000);
+            testCase.verifyEqual(nMonths, uint8(14));
+            testCase.verifyEqual(nDays, uint8(0));
+            testCase.verifyTrue(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_jun18_noleap(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(169, 2001);
+            testCase.verifyEqual(nMonths, uint8(7));
+            testCase.verifyEqual(nDays, uint8(1));
+            testCase.verifyFalse(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_dec31_noleap(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(365, 2001);
+            testCase.verifyEqual(nMonths, uint8(14));
+            testCase.verifyEqual(nDays, uint8(0));
+            testCase.verifyFalse(leaped);
+            testCase.verifyTrue(yeared);
+        end
+
+        function test_dec31_leap(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(366, 2000);
+            testCase.verifyEqual(nMonths, uint8(14));
+            testCase.verifyEqual(nDays, uint8(0));
+            testCase.verifyTrue(leaped);
+            testCase.verifyTrue(yeared);
+        end
+
+        function test_today(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths(363, 2024);
+            testCase.verifyEqual(nMonths, uint8(13));
+            testCase.verifyEqual(nDays, uint8(26));
+            testCase.verifyTrue(leaped);
+            testCase.verifyFalse(yeared);
+        end
+
+        function test_vectorized(testCase)
+            [nMonths, nDays, leaped, yeared] = IFCmonths([1; 31; 168; 168; 169; 169; 365; 366; 363], [2000; 2000; 2000; 2001; 2000; 2001; 2001; 2000; 2024]);
+            testCase.verifyEqual(nMonths, uint8([1; 2; 6; 6; 14; 7; 14; 14; 13]));
+            testCase.verifyEqual(nDays, uint8([1; 3; 28; 28; 0; 1; 0; 0; 26]));
+            testCase.verifyEqual(leaped, [false; false; false; false; true; false; false; true; true]);
+            testCase.verifyEqual(yeared, [false; false; false; false; false; false; true; true; false]);
+        end 
+    end
+    
+end

test_isLeap.m

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+classdef test_isLeap < matlab.unittest.TestCase
+    
+    methods(TestClassSetup)
+        % Shared setup for the entire test class
+    end
+    
+    methods(TestMethodSetup)
+        % Setup for each test
+    end
+    
+    methods(Test)
+        % Test methods
+        
+        function test_basic_2001(testCase)
+            testCase.verifyFalse(isLeap(2001));
+        end
+
+        function test_basic_1996(testCase)
+            testCase.verifyTrue(isLeap(1996));
+        end
+
+        function test_exception1_2100(testCase)
+            testCase.verifyFalse(isLeap(2100));
+        end
+
+        function test_exception2_2000(testCase)
+            testCase.verifyTrue(isLeap(2000));
+        end
+
+        function test_vectorized_all(testCase)
+            testCase.verifyEqual([true; false; false; false; true; false], isLeap([2000; 1999; 1998; 1997; 1996; 2100]));
+        end
+    end
+    
+end