Data commit

Task/Fibonacci-sequence/R/fibonacci-sequence-1.r

@@ -0,0 +1,6 @@
+fib=function(n,x=c(0,1)) {
+   if (abs(n)>1) for (i in seq(abs(n)-1)) x=c(x[2],sum(x))
+   if (n<0) return(x[2]*(-1)^(abs(n)-1)) else if (n) return(x[2]) else return(0)
+}
+
+sapply(seq(-31,31),fib)

Task/Fibonacci-sequence/R/fibonacci-sequence-2.r

@@ -0,0 +1,39 @@
+# recursive
+recfibo <- function(n) {
+  if ( n < 2 ) n
+  else Recall(n-1) + Recall(n-2)
+}
+
+# print the first 21 elements
+print.table(lapply(0:20, recfibo))
+
+# iterative
+iterfibo <- function(n) {
+  if ( n < 2 )
+    n
+  else {
+    f <- c(0, 1)
+    for (i in 2:n) {
+      t <- f[2]
+      f[2] <- sum(f)
+      f[1] <- t
+    }
+    f[2]
+  }
+}
+
+print.table(lapply(0:20, iterfibo))
+
+# iterative but looping replaced by map-reduce'ing
+funcfibo <- function(n) {
+  if (n < 2)
+    n
+  else {
+    generator <- function(f, ...) {
+      c(f[2], sum(f))
+    }
+    Reduce(generator, 2:n, c(0,1))[2]
+  }
+}
+
+print.table(lapply(0:20, funcfibo))