├── Makefile
├── README.md
└── matrix.c


/Makefile:
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1 | all:
2 | 	gcc -Wall -std=c99 -o matrix matrix.c
3 | 
4 | clean:
5 | 	rm -f matrix
6 | 


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/README.md:
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 1 | # Introduction
 2 | 
 3 | Sample matrix implementation illustrating object-oriented techniques in C99.
 4 | 
 5 | It is clear that the techniques presented here have not the pretension to
 6 | replace C++, but it provides enough to do serious object-oriented
 7 | programming:
 8 | 
 9 | * The procedural model using C functions
10 | * The abstract data type model using public interface and private
11 |   implementation as well as data and names encapsulation.
12 | * The object-oriented model using (multiple) inheritance and polymorphism
13 |   which allows to manipulate different object types through a common
14 |   interface.
15 | 
16 | ## Further Reading
17 | * [Matrix Mul](https://msdn.microsoft.com/zh-tw/library/hh873134.aspx)
18 | 


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/matrix.c:
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 1 | #include <stdbool.h>
 2 | 
 3 | typedef struct __matrix_impl Matrix;
 4 | struct __matrix_impl {
 5 |     float values[4][4];
 6 | 
 7 |     /* operations */
 8 |     bool (*equal)(const Matrix, const Matrix);
 9 |     Matrix (*mul)(const Matrix, const Matrix);
10 | };
11 | 
12 | static const float epsilon = 1 / 10000.0;
13 | 
14 | static bool equal(const Matrix a, const Matrix b)
15 | {
16 |     for (int i = 0; i < 4; i++)
17 |         for (int j = 0; j < 4; j++)
18 |             if (a.values[i][j] + epsilon < b.values[i][j]
19 |                     || b.values[i][j] + epsilon < a.values[i][j])
20 |                 return false;
21 |     return true;
22 | }
23 | 
24 | static Matrix mul(const Matrix a, const Matrix b)
25 | {
26 |     Matrix matrix = { .values = {
27 |             { 0, 0, 0, 0, },
28 |             { 0, 0, 0, 0, },
29 |             { 0, 0, 0, 0, },
30 |             { 0, 0, 0, 0, },
31 |         },
32 |     };
33 | 
34 |     for (int i = 0; i < 4; i++)
35 |         for (int j = 0; j < 4; j++)
36 |             for (int k = 0; k < 4; k++)
37 |                 matrix.values[i][j] += a.values[i][k] * b.values[k][j];
38 | 
39 |     return matrix;
40 | }
41 | 
42 | int main()
43 | {
44 |     Matrix m = {
45 |         .equal = equal,
46 |         .mul = mul,
47 |         .values = {
48 |             { 1, 2, 3, 4, },
49 |             { 5, 6, 7, 8, },
50 |             { 1, 2, 3, 4, },
51 |             { 5, 6, 7, 8, },
52 |         },
53 |     };
54 | 
55 |     Matrix n = {
56 |         .equal = equal,
57 |         .mul = mul,
58 |         .values = {
59 |             { 1, 2, 3, 4, },
60 |             { 5, 6, 7, 8, },
61 |             { 1, 2, 3, 4, },
62 |             { 5, 6, 7, 8, },
63 |         },
64 |     };
65 | 
66 |     Matrix o = { .mul = mul, };
67 |     o = o.mul(m, n);
68 | 
69 |     return m.equal(o, (Matrix) {
70 |         .values = {
71 |             { 34,  44,  54,  64, },
72 |             { 82, 108, 134, 160, },
73 |             { 34,  44,  54,  64, },
74 |             { 82, 108, 134, 160, },
75 |         },
76 |     });
77 | }
78 | 


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