Data commit

Task/Cholesky-decomposition/Racket/cholesky-decomposition-1.rkt

@@ -0,0 +1,28 @@
+#lang racket
+(require math)
+
+(define (cholesky A)
+  (define mref matrix-ref)
+  (define n (matrix-num-rows A))
+  (define L (for/vector ([_ n]) (for/vector ([_ n]) 0)))
+  (define (set L i j x) (vector-set! (vector-ref L i) j x))
+  (define (ref L i j) (vector-ref (vector-ref L i) j))
+  (for* ([i n] [k n])
+    (set L i k
+         (cond
+           [(= i k)
+            (sqrt (- (mref A i i) (for/sum ([j k]) (sqr (ref L k j)))))]
+           [(> i k)
+            (/ (- (mref A i k) (for/sum ([j k]) (* (ref L i j) (ref L k j))))
+               (ref L k k))]
+           [else 0])))
+  L)
+
+(cholesky (matrix [[25 15 -5]
+                   [15 18  0]
+                   [-5  0 11]]))
+
+(cholesky (matrix [[18 22  54 42]
+                   [22 70  86 62]
+                   [54 86 174 134]
+                   [42 62 134 106]]))

Task/Cholesky-decomposition/Racket/cholesky-decomposition-2.rkt

@@ -0,0 +1,7 @@
+'#(#(5 0 0)
+   #(3 3 0)
+   #(-1 1 3))
+'#(#(4.242640687119285 0 0 0)
+   #( 5.185449728701349 6.565905201197403  0                  0)
+   #(12.727922061357857 3.0460384954008553 1.6497422479090704 0)
+   #( 9.899494936611665 1.6245538642137891 1.849711005231382  1.3926212476455924))