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quadratc.h
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1 /**********************************************************************
2 * File: quadratc.h (Formerly quadrtic.h)
3 * Description: Code for the QUAD_COEFFS class.
4 * Author: Ray Smith
5 * Created: Tue Oct 08 17:24:40 BST 1991
6 *
7 * (C) Copyright 1991, Hewlett-Packard Ltd.
8 ** Licensed under the Apache License, Version 2.0 (the "License");
9 ** you may not use this file except in compliance with the License.
10 ** You may obtain a copy of the License at
11 ** http://www.apache.org/licenses/LICENSE-2.0
12 ** Unless required by applicable law or agreed to in writing, software
13 ** distributed under the License is distributed on an "AS IS" BASIS,
14 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 ** See the License for the specific language governing permissions and
16 ** limitations under the License.
17 *
18 **********************************************************************/
19
20 #ifndef QUADRATC_H
21 #define QUADRATC_H
22
23 #include "points.h"
24
25 class QUAD_COEFFS
26 {
27 public:
28 QUAD_COEFFS() {
29 } //empty constructor
30 QUAD_COEFFS( //constructor
31 double xsq, //coefficients
32 float x,
33 float constant) {
34 a = xsq;
35 b = x;
36 c = constant;
37 }
38
39 float y( //evaluate
40 float x) const { //at x
41 return (float) ((a * x + b) * x + c);
42 }
43
44 void move( // reposition word
45 ICOORD vec) { // by vector
46 /************************************************************
47 y - q = a (x - p)^2 + b (x - p) + c
48 y - q = ax^2 - 2apx + ap^2 + bx - bp + c
49 y = ax^2 + (b - 2ap)x + (c - bp + ap^2 + q)
50 ************************************************************/
51 inT16 p = vec.x ();
52 inT16 q = vec.y ();
53
54 c = (float) (c - b * p + a * p * p + q);
55 b = (float) (b - 2 * a * p);
56 }
57
58 double a; //x squared
59 float b; //x
60 float c; //constant
61 private:
62 };
63 #endif