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;;;; copyright 2016 rsiddharth <s@ricketyspace.net>
;;;; under gnu general public license version 3 or higher.
(define-module (net ricketyspace taocp utils math)
#:use-module (srfi srfi-1)
#:export (compute-exp1-n
fib
fib-range))
(define (compute-exp1-n fx n)
"Evaluate function FX for `x` equals 1 to N and return all results
as a list
Expression FX is a function that takes exactly one arugment.
For instance `(lambda (x) (* x x))` is a valid FX.
"
(cond ((= n 0) '())
(else (cons (fx n) (compute-exp1-n fx (1- n))))))
(define (fib n)
"Returns Fibonacci of N.
This function is useless for large values of N. Use `fib-fast`
function defined in (taocp one two eight fib).
"
(cond ((= n 0) 0)
((= n 1) 1)
(else (+ (fib (- n 1)) (fib (- n 2))))))
(define (fib-range start end)
"Returns Fibonacci sequence between START and END.
This function is useless wher START/END is large. Use `fib-fast-range`
function defined in (taocp one two eight fib).
"
(let ((f (lambda (x) (cons x (fib x))))
(count (1+ (- end start ))))
(map f (iota count start))))
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