Square root of LISP

Combined Evaluation Rules
1. Evaluate the combined subexpressions
2. Apply the process that serves as the value of the leftmost subexpression (operator) to the corresponding actual parameter. The so-called actual parameter is the value of other subexpressions (operation objects ).

In order to evaluate a combined element, the same process must be executed for each element in the combined element. In terms of nature, this process is recursive.

 

(Define (square X) (* X) (define (average x y) (/(+ x y) 2) (define (sqrt x) (define (good-enough? Guess X) (<(ABS (-(square guess) x) 0.0001) (define (improve guess X) (average guess (/X guess ))) (define (SQRT-iter guess X) (if (good-enough? Guess X) Guess (SQRT-ITER (improve guess X) (SQRT-iter 1.0 X) (define (sqrt2 X) (define (good-enough? Guess) (<(ABS (-(square guess) x) 0.0001) (define (improve guess) (average guess (/X guess ))) (define (SQRT-iter guess) (if (good-enough? Guess) Guess (SQRT-ITER (improve guess) (SQRT-iter 1.0 ))