Data update

Task/Multiple-regression/True-BASIC/multiple-regression.basic

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+OPTION BASE 0
+LET n = 14                        ! number of points and M.R. polynom degree
+LET m = 2
+LET q = 3
+DIM x(0)                          ! data points
+MAT REDIM x(n)
+DATA 1.47, 1.50, 1.52, 1.55, 1.57, 1.60, 1.63, 1.65, 1.68, 1.70, 1.73, 1.75, 1.78, 1.80, 1.83
+FOR c = LBOUND(x) TO UBOUND(x)
+    READ x(c)
+NEXT c
+DIM y(0)                          ! data points
+MAT REDIM y(n)
+DATA 52.21, 53.12, 54.48, 55.84, 57.20, 58.57, 59.93, 61.29, 63.11, 64.47, 66.28, 68.10, 69.92, 72.19, 74.46
+FOR c = LBOUND(y) TO UBOUND(y)
+    READ y(c)
+NEXT c
+DIM s(0)                          ! linear system coefficient
+MAT REDIM s(n)
+DIM t(0)
+MAT REDIM t(n)
+DIM a(0,0)                        ! system to be solved
+MAT REDIM a(m, q)
+DIM p(0,0)
+MAT REDIM p(m, q)
+
+FOR k = 0 TO 2*m
+    LET s(k) = 0
+    LET t(k) = 0
+    FOR i = 0 TO n
+        LET s(k) = s(k)+x(i)^k
+        IF k <= m THEN LET t(k) = t(k)+y(i)*x(i)^k
+    NEXT i
+NEXT k
+! build linear system
+FOR fila = 0 TO m
+    FOR columna = 0 TO m
+        LET a(fila, columna) = s(fila+columna)
+    NEXT columna
+    LET a(fila, columna) = t(fila)
+NEXT fila
+PRINT "Linear system coefficents:"
+FOR i = 0 TO m
+    FOR j = 0 TO m+1
+        PRINT  USING "######.#": a(i, j);
+    NEXT j
+    PRINT
+NEXT i
+FOR j = 0 TO m
+    FOR i = j TO m
+        IF a(i, j) <> 0 THEN EXIT FOR
+    NEXT i
+    IF i = m+1 THEN
+       PRINT
+       PRINT "SINGULAR MATRIX '"
+       STOP
+    END IF
+    FOR k = 0 TO m+1
+        LET p(j, k) = a(i, k)
+        LET a(i, k) = p(j, k)
+        LET a(j, k) = a(i, k)
+    NEXT k
+    LET z = 1/a(j, j)
+    FOR k = 0 TO m+1
+        LET a(j, k) = z*a(j, k)
+    NEXT k
+    FOR i = 0 TO m
+        IF i <> j THEN
+           LET z = -a(i, j)
+           FOR k = 0 TO m+1
+               LET a(i, k) = a(i, k)+z*a(j, k)
+           NEXT k
+        END IF
+    NEXT i
+NEXT j
+PRINT
+PRINT "Solutions:"
+FOR i = 0 TO m
+    PRINT  USING "  #####.#######": a(i, m+1);
+NEXT i
+END