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Java 稀疏数组的快速标量乘法。
稀疏数组的快速标量乘法。
实例源码：
源代码：
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//N o w J a v a . c o m 提 供2
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//package com.nowjava;5
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public class Main {8
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public static void main(String[] argv) throws Exception {10
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double a = 2.45678;12
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double[] v = new double[] { 34.45, 35.45, 36.67, 37.78, 37.0000,14
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37.1234, 67.2344, 68.34534, 69.87700 };16
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System.out.println(java.util.Arrays.toString(scalarMultiplyFast(a,18
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v)));20
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}22
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/**25
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* Fast scalar multiplication for sparse arrays.27
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*/29
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public static double[] scalarMultiplyFast(double a, double[] v) {31
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if (a == 0.0)33
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return (new double[v.length]);35
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double[] ans = new double[v.length];37
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for (int k = 0; k < v.length; k++) {39
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if ((a != 0.0) && (v[k] != 0)) {41
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ans[k] = v[k] * a;43
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} else45
/* from 46
N o w J a v a . c o m - 时 代 Java*/47
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ans[k] = 0.0;49
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}51
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return (ans);53
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}55
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/**58
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* Fast scalar multiplication for sparse arrays.60
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*/62
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public static double[] scalarMultiplyFast(double a, int[] v) {64
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if (a == 0.0)66
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return (new double[v.length]);68
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double[] ans = new double[v.length];70
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for (int k = 0; k < v.length; k++) {72
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if ((a != 0) && (v[k] != 0)) {74
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ans[k] = v[k] * a;76
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} else78
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ans[k] = 0.0;80
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}82
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return (ans);84
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}86
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/**89
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* Returns a comma delimited string representing the value of the array.91
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*/93
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public static String toString(double[] array) {95
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StringBuffer buf = new StringBuffer(array.length);98
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int i;100
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for (i = 0; i < array.length - 1; i++) {102
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buf.append(array[i]);104
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buf.append(',');106
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}108
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buf.append(array[i]);110
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return buf.toString();112
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}114
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/**117
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* Returns a comma delimited string representing the value of the array.119
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*/121
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public static String toString(double[][] array) {123
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StringBuffer buf = new StringBuffer();125
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for (int k = 0; k < array.length; k++) {127
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buf.append(toString(array[k]));129
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buf.append(System.getProperty("line.separator"));131
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}133
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return buf.toString();135
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}137
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/**140
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* Returns a comma delimited string representing the value of the array.142
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*/144
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public static String toString(int[] array) {146
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StringBuffer buf = new StringBuffer(array.length);148
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int i;150
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for (i = 0; i < array.length - 1; i++) {152
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buf.append(array[i]);154
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buf.append(',');156
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}158
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