xvals = 0.9:0.025:1... %list of values for your loop
for X = xvals
....
end
nearest975 = interp1(xvals, xvals, 0.975, 'nearest');
for X = nearest975
...
end
In this way, nearest975 will be an exact copy of one of the values in the list xvals, which is the list you looped over.
Also, generally speaking linspace() has higher accuracy than the colon operator.
You would use the colon operator in a "for" loop instead of linspace if memory space is tight, in that linspace will create the complete list of values and store it, but the colon operator in a for loop will not store the values ahead of time and will generate them as needed. (Note: in the code I show above, the colon operator is not being used in a for loop, so the values will be generated and stored.)
