'Contract Violation; expected: real?; given #f

I'm sorry if this question has been answered before, but I've looked around and I can't really understand the explanation as to why I'm getting this error.

From what I understand I'm asking if a statement is true and then if it is I'm asking it to return an expression. And apparently I'm not allowed to get #t/#f answers and expressions? I'm not sure. Could someone help me understand.

This is my code.

(define (piecewise x)
  (define pi 3.142)
  (cond
    ((> x (* pi 2)) (- x (* 2 pi)))
    ((or ( > x (* pi -1) (= x ( * -1 pi)))) (sin x))
    ((or ( < x (* 2 pi)) (= x (* 2 pi))) (sin x))
    (else (- (- 1 x) pi))))
scheme


Solution 1:[1]

If I may, if we take all of the suggestions and use them to simplify the code a bit, we might get the following:

(define (piecewise x)
  (let* ((pi 3.142)
         (tau (* 2 pi)))
    (cond
     ((> x tau) 
      (- x tau))
     ((or (>= x (- pi))
          (<= x tau))
      (sin x))
     (else (+ x pi)))))

This runs without errors under both Racket and Guile. Whether it computes the function correctly, only the OP can say for certain.

Sources

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Source: Stack Overflow

Solution Source
Solution 1

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