Data commit

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-1.tcl

@@ -0,0 +1,9 @@
+proc fibiter n {
+    if {$n < 2} {return $n}
+    set prev 1
+    set fib 1
+    for {set i 2} {$i < $n} {incr i} {
+        lassign [list $fib [incr fib $prev]] prev fib
+    }
+    return $fib
+}

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-2.tcl

@@ -0,0 +1,3 @@
+proc fib {n} {
+    if {$n < 2} then {expr {$n}} else {expr {[fib [expr {$n-1}]]+[fib [expr {$n-2}]]} }
+}

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-3.tcl

@@ -0,0 +1,11 @@
+proc tcl::mathfunc::fib {n} {
+    if { $n < 2 } {
+        return $n
+    } else {
+        return [expr {fib($n-1) + fib($n-2)}]
+    }
+}
+
+# or, more tersely
+
+proc tcl::mathfunc::fib {n} {expr {$n<2 ? $n : fib($n-1) + fib($n-2)}}

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-4.tcl

@@ -0,0 +1,4 @@
+expr {fib(7)} ;# ==> 13
+
+namespace path tcl::mathfunc #; or, interp alias {} fib {} tcl::mathfunc::fib
+fib 7 ;# ==> 13

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-5.tcl

@@ -0,0 +1,12 @@
+proc fib-tailrec {n} {
+    proc fib:inner {a b n} {
+        if {$n < 1} {
+            return $a
+        } elseif {$n == 1} {
+            return $b
+        } else {
+            tailcall fib:inner $b [expr {$a + $b}] [expr {$n - 1}]
+        }
+    }
+    return [fib:inner 0 1 $n]
+}

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-6.tcl

@@ -0,0 +1,17 @@
+proc fibiter n {
+    if {$n < 0} {
+        set n [expr {abs($n)}]
+        set sign [expr {-1**($n+1)}]
+    } else {
+        set sign 1
+    }
+    if {$n < 2} {return $n}
+    set prev 1
+    set fib 1
+    for {set i 2} {$i < $n} {incr i} {
+        lassign [list $fib [incr fib $prev]] prev fib
+    }
+    return [expr {$sign * $fib}]
+}
+fibiter -5 ;# ==> 5
+fibiter -6 ;# ==> -8

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-7.tcl

@@ -0,0 +1,3 @@
+proc tcl::mathfunc::fib {n} {expr {$n<-1 ? -1**($n+1) * fib(abs($n)) : $n<2 ? $n : fib($n-1) + fib($n-2)}}
+expr {fib(-5)} ;# ==> 5
+expr {fib(-6)} ;# ==> -8

Task/Fibonacci-sequence/Tcl/fibonacci-sequence-8.tcl

@@ -0,0 +1 @@
+proc fib n {expr {round((.5 + .5*sqrt(5)) ** $n / sqrt(5))}}