Area Under Curve / Volume of Solid of Revolution

aucvosor.rkt

#lang racket

;; Compute the area under a curve and the volume of the solid between L and R
;; first line is the bases, second is the exponents, third is the L and R limits
(define bases (map string->number (string-split (read-line) " ")))
(define expos (map string->number (string-split (read-line) " ")))
(define-values
 (left right)
 (apply values (map string->number (string-split (read-line) " "))))

(define (crunch x)
  (define (ic x acc b e)
    (if (empty? b)
        acc
        (ic x
            (+ acc (* (car b) (expt x (car e))))
            (cdr b)
            (cdr e))))
  (ic x 0 bases expos))

(define (riemman-sum l r f)
  (define (is l r acc)
    (if (>= l r)
        acc
        (is (+ l 0.001) r (+ acc (* 0.001 (f (crunch l)))))))
  (is l r 0))

(displayln (real->decimal-string (riemman-sum left right (λ (x) x)) 1))
(displayln (real->decimal-string (riemman-sum left right (λ (x) (* pi (expt x 2)))) 1))