Looking to find values in an array that are within a small percent of another array.

I am looking to find time values between 0 and 10 seconds in which the relative time values within one array falls within (a+delta, a-delta) of the other array whose value is "a", for every incremental step of 1 millisecond of array "a". How do I do this? If you need clarification, please ask.

[Walter Roberson]

is delta a fixed value or a "percent" ? If it is a percent, is it a percent that is calculated once for the entire array or is it a percent to be calculated for each element?

I do not understand about 'every incremental step of 1 millisecond of array "a"'. Please show a small example that shows that and which shows what data structure you want for the output.