Undefined function 'quorem' for input arguments of type 'double'

I'm getting this error when I run the file. The quorem seems to be a function when I search in help so I don't understand why I'm getting this error. help

Undefined function 'quorem' for input arguments of type 'double'. Error in Test1 (line 13) [q, r] = quorem(nRowh,20)

clear
load A_Day.mat

fts1 = fints(Time,Data,{'Open','High','Low','Close'})

close = fts2mat(fts1.Close)
high = fts2mat(fts1.High)
low = fts2mat(fts1.Low)
middle=(high+low)/2;
dates=datenum(Time);
window_size=20;
[nRowh,nColh]=size(high);
[q, r] = quorem(nRowh,20)

Answer 1

[KSSV]

      use 

[q, r] = quorem(sym(nRowh),sym(20))

quorem works on symbolic variables. Convert your double to sym using sym