; CS101, Spring 2013
; Lab 2 Racket starter file



; Defining unnamed procedures using the lambda special form.

; NOTE: All parts that are to be completed by you are inside comment
;       boxes.  Read everything up to the comment box and then write
;       your answers and choose Uncomment under the Racket menu. If
;       you are reading this file as a text file, the comment boxes
;       are not shown.

(display "\n         CS101 Lab 2, Spring 2013\n")
(display "\n         PLEASE WRITE YOUR NAME HERE\n\n")
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(display "Problem 1(a): Writing a Fahrenheit to Celsius converter:\n\n")

;;    Define an unnamed Racket procedure that consumes a single
;;    input (representing the temperature in Fahrenheit) and returns   
;;    as output the corresponding temperature in Celsius.
;;    
;;    The appropriate conversion formula is:  c = 5(f-32)/9.
;;    (You'll have to change this expression a little to get it
;;    into the form of a Racket expression.)
;;    
;;    Make sure that you test your unnamed procedure on the
;;    following examples:
;;    
;;           f = 32, f = 212, and f = -40.
    

; ; UNCOMMENT THE PRINTF BELOW AND WRITE THE LAMBDA EXPRESSION IN THE 
; ; PRINTF STATEMENT. WRITE THE LAMBDA EXPRESSION IN A STRING AS THE
; ; SECOND ARGUMENT TO PRINTF AS INDICATED BELOW.
;  
; (printf "Solution is:  ~a~%~%" "WRITE LAMBDA EXPRESSION AS A STRING HERE")
; 


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;; CALL THE LAMBDA EXPRESSION YOU WROTE ABOVE ON THE 3 INPUTS 
;; f=32, f=212, f=-40. 
;;
;; THERE SHOULD BE 3 SEPARATE CALLS TO PRINTF, AS STARTED BELOW. 
;;
;; EACH PRINTF EXPRESSION SHOULD HAVE 3 ARGUMENTS:
;;     1ST ARG: the string "~a degrees F = ~a degrees C~%~%" (GIVEN),
;;     2ND ARG: a number representing the temperature in degrees Fahrenheit
;;              (GIVEN),
;;     3RD ARG: a call to the lambda function you wrote above, passing in the 
;;              degrees Fahrenheit as an argument to the lambda function.

; ;; 3 INPUTS f=32, f=212, f=-40
; 
; (printf "~a degrees F = ~a degrees C~%~%" ...)      
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; (printf "~a degrees F = ~a degrees C~%~%" ...)
; (newline)
; (printf "~a degrees F = ~a degrees C~%~%" ...)
; 



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(display "Problem 1(b): Naming the lambda expression from part 1(a):\n\n")

;;    Use a define special form to name the lambda expression you wrote 
;;    for part (a). Call the function fahr->cels.
;;    
;;    Test the fahr->cels procedure on the following examples:  
;;    
;;               f = 32, f = 212, and f = -40.
;;    

; ;; DEFINE THE FAHR->CELS FUNCTION HERE.                     
; 
; 
; 



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;; CALL FAHR->CELS WITH THE SAME INPUTS YOU USED IN PART (a) USING THREE
;; PRINTF STATEMENTS WITH THE SAME NUMBER OF ARGUMENTS AS THE ONES IN 1(a).
;; (3 SEPARATE PRINTF STATEMENTS).

;  ;; 3 INPUTS f=32, f=212, f=-40
; 
; (printf "~a degrees F = ~a degrees C~%~%" ...)              
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; (printf "~a degrees F = ~a degrees C~%~%" ...)
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; (printf "~a degrees F = ~a degrees C~%~%" ...)
; 


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(display "Problem 2(a): Writing a function to calculate slope:\n\n")

;;    Define an unnamed Racket procedure that consumes four           
;;    inputs--x1, y1, x2, y2--representing the coordinates of
;;    two points in the xy-plane: (x1, y1) and (x2, y2), and 
;;    returns as output the slope of the line segment joining
;;    these two points.
;;    
;;    The appropriate formula is:  (y2 - y1) / (x2 - x1).
;;    (You'll have to change this expression a little to get 
;;    it into the form of a Racket expression.) You may assume
;;    that x1 and x2 are different.
;;    
;;    Make sure that you test the unnamed procedure on the
;;    following examples:  
;;    
;;    x1 = 0, y1 = 0, x2 = 1, y2 = 1
;;    
;;    x1 = 0, y1 = 0, x2 = 3, y2 = 12
;;    
;;    x1 = 1, y1 = 2, x2 = 8, y2 = 15
    

; ; WRITE THE LAMBDA EXPRESSION IN A PRINTF STATEMENT. WRITE THE 
; ; LAMBDA EXPRESSION IN A STRING AS THE SECOND ARGUMENT TO PRINTF,
; ; AS INDICATED BELOW.
; 
; (printf "Solution is:  ~a~%~%" "WRITE LAMBDA EXPRESSION HERE")
; 


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;; CALL THE LAMBDA EXPRESSION ON THE 3 SETS OF INPUTS GIVEN ABOVE 
;; EACH PRINTF EXPRESSION SHOULD HAVE 6 ARGUMENTS:
;;     1ST ARG: the string "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"
;;              (STRING IS GIVEN BELOW FOR EACH SET OF ARGUMENTS),
;;     2ND THROUGH 5TH ARGS: values for x1, x2, y1, and y2 (GIVEN)
;;     6TH ARG: a call to the lambda function you wrote above, passing in 
;;              x1 x2 y1 and y2.

;  ;; 3 INPUTS  x1 = 0, y1 = 0, x2 = 1, y2 = 1
;  ;;           x1 = 0, y1 = 0, x2 = 3, y2 = 12
;  ;;           x1 = 1, y1 = 2, x2 = 8, y2 = 15
; 
; (printf "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"      
;         ...)
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; (printf "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"
;         ...)
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; (printf "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"
;         ...)

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(display "Problem 2(b): Naming the lambda expression from part 2(a):\n")

;;    Use a define special form to name the lambda expression you wrote 
;;    for part 2(a). Call the function slope.
;;    
;;    Test the slope procedure on the same examples as you did in part
;;    2(a).
;;    

; ;; DEFINE THE SLOPE FUNCTION HERE.                           
; 
; 



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;; CALL THE SLOPE FUNCTION WITH THE SAME INPUTS YOU USED IN PART (a) 
;; (3 SEPARATE PRINTF STATEMENTS WITH 6 ARGUMENTS EACH).

;  ;; 3 INPUTS  x1 = 0, y1 = 0, x2 = 1, y2 = 1
;  ;;           x1 = 0, y1 = 0, x2 = 3, y2 = 12
;  ;;           x1 = 1, y1 = 2, x2 = 8, y2 = 15
; 
; (printf "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"     
;         ...)
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; (printf "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"
;         ...)
; (newline)
; (printf "Slope when x1=~a, y1=~a, x2=~a, y2=~a is ~a~%~%"
;         ...)


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