Changeset 34:ee0188025de8 in roaraudio

Timestamp:

06/22/08 03:31:39 (16 years ago)

Author:

phi

Branch:

default

Phase:

public

Message:

added some polynom approxy code

File:

• libroardsp/poly.c (modified) (1 diff)

libroardsp/poly.c

@@ -3 +3 @@
 #include "libroar.h"
 
-int roar_math_mkpoly (float * poly, float * data, int len);
+int roar_math_mkpoly (float * poly, float * data, int len) {
+ if ( len == 2 )
+  return roar_math_mkpoly_2x2(poly, data);
+ if ( len == 3 )
+  return roar_math_mkpoly_3x3(poly, data);
+ if ( len == 4 )
+  return roar_math_mkpoly_4x4(poly, data);
+ if ( len == 5 )
+  return roar_math_mkpoly_5x5(poly, data);
 
-int roar_math_mkpoly_2x2 (float * poly, float * data);
-int roar_math_mkpoly_3x3 (float * poly, float * data);
-int roar_math_mkpoly_4x4 (float * poly, float * data);
+ return -1;
+}
+
+int roar_math_mkpoly_2x2 (float * poly, float * data) {
+/*
+ A B
+ 0 1 x
+ 1 1 y
+
+B = x
+A = y - x
+*/
+
+ poly[0] =           data[0];
+ poly[1] = data[1] - data[0];
+
+ return 0;
+}
+
+int roar_math_mkpoly_3x3 (float * poly, float * data) {
+/*
+ A B C
+ 0 0 1 x
+ 1 1 1 y
+ 4 2 1 z
+*/
+
+ poly[0] = data[0];
+ poly[1] = 2*data[1] - 2*data[0] - (data[2]-data[0])/2;
+ poly[2] = (data[2]-data[0])/2 - data[1] + data[0];
+
+
+ return 0;
+}
+
+int roar_math_mkpoly_4x4 (float * poly, float * data) {
+/*
+   a    b    c    d
+   0    0    0    1  A X 0
+   1    1    1    1  B Y 1
+   8    4    2    1  C Z 2
+  27    9    3    1  D Q 3
+*/
+
+
+// { a = -(3z-3y+x-q)/6, b = (4z-5y+2x-q)/2, c = -(9z-18y+11x-2q)/6, d = x }.
+
+ poly[0] =      data[0];
+ poly[1] = -(11*data[0] - 18*data[1] + 9*data[2] - 2*data[3])/6;
+ poly[2] =  (2 *data[0] -  5*data[1] + 4*data[2] -   data[3])/2;
+ poly[3] = -(   data[0] -  3*data[1] + 3*data[2] -   data[3])/6;
+
+ return 0;
+}
+
 int roar_math_mkpoly_5x5 (float * poly, float * data);