FilesExpand file tree

 master

/

Matrix.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

259 lines (209 loc) · 6.85 KB

 master

/

Matrix.java

Top

File metadata and controls

• Code
• Blame

259 lines (209 loc) · 6.85 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

/**

* Matrix data-type.

*

* @author Kyler Smith, 2017

*/

public class Matrix {

public static void main(String[] args) {

int[][] data1 = new int[0][0];

int[][] data2 = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

int[][] data3 = {{1, 4, 7}, {2, 5, 8}, {3, 6, 9}};

Matrix m1 = new Matrix(data1);

Matrix m2 = new Matrix(data2);

Matrix m3 = new Matrix(data3);

System.out.println("m1 --> Rows: " + m1.getRows() + " Columns: " + m1.getColumns());

System.out.println("m2 --> Rows: " + m2.getRows() + " Columns: " + m2.getColumns());

System.out.println("m3 --> Rows: " + m3.getRows() + " Columns: " + m3.getColumns());

//check for reference issues

System.out.println("m2 -->\n" + m2);

data2[1][1] = 101;

System.out.println("m2 -->\n" + m2);

//test equals

System.out.println("m2==null: " + m2.equals(null)); //false

System.out.println("m3==\"MATRIX\": " + m2.equals("MATRIX")); //false

System.out.println("m2==m1: " + m2.equals(m1)); //false

System.out.println("m2==m2: " + m2.equals(m2)); //true

System.out.println("m2==m3: " + m2.equals(m3)); //false

//test operations (valid)

System.out.println("2 * m2:\n" + m2.scale(2));

System.out.println("m2 / 2:\n" + m2.divide(2));

System.out.println("m2 + m3:\n" + m2.plus(m3));

System.out.println("m2 - m3:\n" + m2.minus(m3));

System.out.println("m2 * m3: \n"+m2.multiply(m3));

}

/**

* Data needs to be a deep copy as not to change the original state.

*/

private int[][] data;

/**

* Constructor for the matrix takes in a 2D array

*

* @param pData

*/

public Matrix(int[][] pData) {

/** Make a deep copy of the data */

if(pData.length != 0) {

int[][] newData = new int[pData.length][pData[0].length];

for(int i = 0; i < pData.length; i++)

for(int j = 0; j < pData[0].length; j++)

newData[i][j] = pData[i][j];

this.data = newData;

} else {

this.data = null;

}

}

/**

* Returns the element specified by the given location

*

* @param x : x cooridinate

* @param y : y cooridinate

* @return int : value at location

*/

public int getElement(int x, int y) {

return data[x][y];

}

/**

* Returns the number of rows in the Matrix

*

* @return rows

*/

public int getRows() {

if(this.data == null)

return 0;

return data.length;

}

/**

* Returns the number of rows in the Matrix

*

* @return columns

*/

public int getColumns() {

if(this.data == null)

return 0;

return data[0].length;

}

/**

* Returns this matrix scaled by a factor. That is, computes sA where s is a

* constant and A is a matrix (this object).

*

* @param scalar : value to scale by

* @return A new matrix scaled by the scalar value

*/

public Matrix scale(int scalar) {

int[][] newData = new int[this.data.length][this.data[0].length];

for (int i = 0; i < this.getRows(); ++i)

for(int j = 0; j < this.getColumns(); ++j)

newData[i][j] = this.data[i][j] * scalar;

return new Matrix(newData);

}

/**

* Returns this matrix divided by a factor. That is, computes sA where s is a

* constant and A is a matrix (this object).

*

* @param scalar : value to divide by

* @return A new matrix scaled by the scalar value

*/

public Matrix divide(int scalar) {

int[][] newData = new int[this.data.length][this.data[0].length];

for (int i = 0; i < this.getRows(); ++i)

for(int j = 0; j < this.getColumns(); ++j)

newData[i][j] = this.data[i][j] / scalar;

return new Matrix(newData);

}

/**

* Adds this matrix to another matrix.

*

* @param other : Matrix to be added

* @return addend

*/

public Matrix plus(Matrix other) throws RuntimeException {

int[][] newData = new int[this.data.length][this.data[0].length];

if(this.getRows() != other.getRows() || this.getColumns() != other.getColumns())

throw new RuntimeException("Not the same size matrix.");

for (int i = 0; i < this.getRows(); ++i)

for(int j = 0; j < this.getColumns(); ++j)

newData[i][j] = this.data[i][j] + other.getElement(i, j);

return new Matrix(newData);

}

/**

* Subtracts this matrix from another matrix.

*

* @param other : Matrix to be subtracted

* @return difference

*/

public Matrix minus(Matrix other) throws RuntimeException {

int[][] newData = new int[this.data.length][this.data[0].length];

if(this.getRows() != other.getRows() || this.getColumns() != other.getColumns())

throw new RuntimeException("Not the same size matrix.");

for (int i = 0; i < this.getRows(); ++i)

for(int j = 0; j < this.getColumns(); ++j)

newData[i][j] = this.data[i][j] - other.getElement(i, j);

return new Matrix(newData);

}

/**

* Multiplies this matrix with another matrix.

*

* @param other : Matrix to be multiplied with

* @return product

*/

public Matrix multiply(Matrix other) throws RuntimeException {

int[][] newData = new int[this.data.length][other.getColumns()];

if(this.getColumns() !=other.getRows())

throw new RuntimeException("The two matrices cannot be multiplied.");

int sum;

for (int i = 0; i < this.getRows(); ++i)

for(int j = 0; j < other.getColumns(); ++j){

sum = 0;

for(int k=0;k<this.getColumns();++k){

sum += this.data[i][k] * other.getElement(k, j);

}

newData[i][j] = sum;

}

return new Matrix(newData);

}

/**

* Checks if the matrix passed is equal to this matrix

*

* @param other : the other matrix

* @return boolean

*/

public boolean equals(Matrix other) {

return this == other;

}

/**

* Returns the Matrix as a String in the following format

*

* [ a b c ] ...

* [ x y z ] ...

* [ i j k ] ...

* ...

*

* @return Matrix as String

* TODO: Work formatting for different digit sizes

*/

public String toString() {

String str = "";

for(int i = 0; i < this.data.length; i++) {

str += "[ ";

for(int j = 0; j < this.data[0].length; j++) {

str += data[i][j];

str += " ";

}

str += "]";

str += "\n";

}

return str;

}

/**

* Returns transposed matrix of this matrix.

*

* @return transposed Matrix.

*/

public Matrix transpose() {

int[][] newData = new int[this.data[0].length][this.data.length];

for (int i = 0; i < this.getColumns(); ++i)

for(int j = 0; j < this.getRows(); ++j)

newData[i][j] = this.data[j][i];

return new Matrix(newData);

}

}