Runge-Kutta method: Difference between revisions

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 676 _5.09833e_5</lang>
-Alternative version:
+'''Alternative solution:'''
-<lang j>p4=: 1 :0
+The following solution replaces the for loop as well as the calculation of the increments (ks) with an accumulating suffix.
+<lang j>nextY=: adverb define
 :
- ({:y)+6%~+/1 2 2 1*(x*[: u y+(*x&,))/\.1 0.5 0.5,x*u y
+ tableau=. 1 0.5 0.5, x * u y
+ ks=. (x * [: u y + (* x&,))/\. tableau
+ ({:y) + 6 %~ +/ 1 2 2 1 * ks
 )
-rk4=: 1 :0
+rk4=: adverb define
  'Y0 a b h'=. 4{. y
- (,.[:h&(u p4)@,/\.Y0,~}.)&.|. a+i.@>:&.(%&h) b-a
+ T=. a + i.@>:&.(%&h) b-a
+ (,. [: h&(u nextY)@,/\. Y0 ,~ }.)&.|. T
 )</lang>