Function and global variable

How to write these function and calling function?

Write a function, f_lab10, that will calculate this series approximation.  Run your series code until the approximate percent relative error (apre) is below a specified error se = 0.01.  Write a main or calling program, fcall_lab10, that will call f_lab10.  You can hard-code se and x in fcall_lab10.  Document f_lab10 and fcall_lab10 fully.  In this lab, we want to compute the series approximation for each value in a vector x = [0:0.04:0.8]; so, in fcall_lab10 you will need a loop that will call f_lab10 once for each value in x. Store the approximation for each value of x in the vector sapprox that you will size before starting you loop, for example, sapprox = zeros(size(x));  Pass the value of x to f_lab10 as an input, pass se to f_lab10 using the Global Memory, and pass the series approximation from f_lab10 to fcall_lab10 as an output of f_lab10.  An example of the first two lines of your function is as follows:

function series_approx=f_lab10(x)
  global  se

Thanks!!

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Looking like a homework question.