Homework Problem 13, Due Monday March 1.
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RECALL from class that for a continuous function f(t) 
defined on the interval [a,a+2*h], 

(i) the Trapezoid Rule approximates the integral of f
on [a,a+h] by:  (h/2)*(f(a)+f(a+h)) ;  and 

(ii) Simpson's Rule approximates the integral of f
on [a,a+2h] by:  (h/3)*(f(a)+4*f(a+h)+f(a+2h)).
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Using first the trapezoid rule and then 
Simpson's rule, code a function which will tabulate
the cumulative distribution function F at 
regularly spaced points  seq(a,b,by=(b-a)/m)
for a density function  f  WHICH IS SPECIFIED AS AN 
INPUT PARAMETER. 

Your function should have input arguments
a,b,m,f and output a vector closely approximating  
F(seq(a,b,by=(b-a)/m)).

Test to make sure that your function works !