Loop for calculating wind chill values

I am trying to calculate the Wind Chill factor for many values of Wind speed and Temp.

I want to only use values when TEMP is less than 50 and wind speed is greater than 3.

I also need the result to be a vector so I can plot all the values. Below us my code

Note that I am reading my wind and tempo values from an excel file. Thanks!

for n=1:length(TEMP)
    if TEMP<50 && WIND>3
    TEMP=dlmread('denver_weather.csv',',',[7,5,0,5]);
    WIND=dlmread('denver_weather.csv',',',[7,12,0,12]);
    WCF(n)=35.7+0.6.*TEMP-35.7.*(WIND.^(.16))+.43.*(WIND.^(.16))
    end
end

Answer 1

[Star Strider]

You didn’t attach ‘denver_weather.csv’ so I can only assume ‘TEMP’ and ‘WIND’ are equal-size vectors.

I would do something like this:

TEMP = dlmread('denver_weather.csv',',',[7,5,0,5]);
WIND = dlmread('denver_weather.csv',',',[7,12,0,12]);
idx = TEMP<50 & WIND>3;                                     % Logical Index 
WCF = 35.7+0.6.*TEMP(idx)-35.7.*(WIND(idx).^(.16))+.43.*(WIND(idx).^(.16));

NOTE — This is obviously UNTESTED CODE. If my assumptions are correct, it should work with minimal modification.

[Mitch White]

Thanks! If I need the WCF array to be the same size to plot against a corresponding date/time, how would I incorporate the days/time when the WCF is zero so that my arrays match up?

My date/time array is the same size as the TEMP and WIND arrays

[Star Strider]

My pleasure!

I would use the ‘idx’ logical vector to select the date/time array just as with the others. They will all then have the same lengths and will correspond so you can plot them.