sicp-ex-3.78



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meteorgan

  
  
  
 (define (solve-2nd a b dt y0 dy0) 
         (define y (integral (delay dy) y0 dt)) 
         (define dy (integral (delay ddy) dy0 dt)) 
         (define ddy (add-streams (scale-stream dy a) (scale-stream y b))) 
         y) 

seok

  
 ; Some test cases to verify an implementation.. 
  
 (stream-ref (solve-2nd 1 0 0.0001 1 1) 10000)  ; e                                                         
 (stream-ref (solve-2nd 0 -1 0.0001 1 0) 10472)  ; cos pi/3 = 0.5                                           
 (stream-ref (solve-2nd 0 -1 0.0001 0 1) 5236)  ; sin pi/6 = 0.5 

asmn

I had the same solution has meteorgan and the program runs out of memory when trying to solve anything. I have memory limit to 1GB as well