Convert time string to 24 hour format then into Decimal using current time clock
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I am trying to convert the variable AST from a string to a number in 24 hour format. I would then like to store AST as a new variable, call it 'ASTdec' in decimal i.e AST at 13:30 = 13.5 so that I can manipulate it with other eqns. AST is the solar time, converted from regular clock time.
background code:
c = clock();
tsNow = datenum(c);
tsStart = datenum([c(1) 1 1 0 0 0]);
daysInYear = tsNow - tsStart;
DayOfYear = floor(daysInYear)+1;
get current LST time in 24 hour format:
datestr(now);
d = rem(now,1);
datestr(d);
time = datestr(d, 'HH:MM');
get apparent solar time AST:
B = 360/365*(DayOfYear-81);
EoT = 9.87*sind(2*B)-7.53*cosd(B)-1.5*sind(B);
Correction = EoT - (4*(0-3.173));
Declination = 23.45*sind((360/365)*(284+DayOfYear));
AST = datestr(d - datenum([0 0 0 0 Correction 0]));
Tried using:
ASTVec = datevec(AST, 'HH:MM');
SolarMinutes = ASTVec(5);
SolarHours = ASTVec(4);
to get the vector and then do manipulation with the vector cells to get my decimal but SolarHours are not in 24 hr format because the string is not in 24 hour format. Variable
Correction
is already a value of time expressed in decimal and is used to define AST.
0 Comments
Accepted Answer
Walter Roberson
on 15 Nov 2013
It looks to me like,
ASTVec = datevec(d - Correction/(24*60));
3 Comments
Walter Roberson
on 15 Nov 2013
Minutes if I have correctly understood your Correction to be in minutes. You would continue on with your existing code,
SolarMinutes = ASTVec(5);
SolarHours = ASTVec(4);
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