| 1 | package de.uka.ipd.sdq.reliability.solver.pcm2markov; |
| 2 | |
| 3 | /** |
| 4 | * This class represents an approximated Markov transformation result value. |
| 5 | * |
| 6 | * @author brosch |
| 7 | * |
| 8 | */ |
| 9 | public class MarkovResultApproximation { |
| 10 | |
| 11 | /** |
| 12 | * The maximal accuracy yielded by an approximation. |
| 13 | */ |
| 14 | private static final int MAXACCURACY = 10; |
| 15 | |
| 16 | /** |
| 17 | * The accuracy (i.e., number of exact decimal places) of this |
| 18 | * approximation. |
| 19 | */ |
| 20 | private int accuracy = 0; |
| 21 | |
| 22 | /** |
| 23 | * The lower approximation bound after adjustment. |
| 24 | */ |
| 25 | private double adjustedLowerBound = 0.0; |
| 26 | |
| 27 | /** |
| 28 | * The upper approximation bound after adjustment. |
| 29 | */ |
| 30 | private double adjustedUpperBound = 0.0; |
| 31 | |
| 32 | /** |
| 33 | * A lower approximation bound. |
| 34 | */ |
| 35 | private double lowerBound = 0.0; |
| 36 | |
| 37 | /** |
| 38 | * An upper approximation bound. |
| 39 | */ |
| 40 | private double upperBound = 0.0; |
| 41 | |
| 42 | /** |
| 43 | * Initializes a new Markov result value approximation. |
| 44 | * |
| 45 | * @param lowerBound |
| 46 | * the lower bound of the approximation |
| 47 | * @param upperBound |
| 48 | * the upper bound of the approximation |
| 49 | */ |
| 50 | public MarkovResultApproximation(final double lowerBound, |
| 51 | final double upperBound) { |
| 52 | this.lowerBound = lowerBound; |
| 53 | this.upperBound = upperBound; |
| 54 | calculateAccuracy(); |
| 55 | adjustBounds(); |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Replaces the approximation through a more coarse-grained one, in order to |
| 60 | * reduce the number of decimal places of the bounds to the value of |
| 61 | * accuracy. |
| 62 | */ |
| 63 | private void adjustBounds() { |
| 64 | adjustedLowerBound = Math |
| 65 | .floor(lowerBound * Math.pow(10, accuracy + 1)) |
| 66 | / Math.pow(10, accuracy + 1); |
| 67 | adjustedUpperBound = Math.ceil(upperBound * Math.pow(10, accuracy + 1)) |
| 68 | / Math.pow(10, accuracy + 1); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Determines the accuracy of the approximation. |
| 73 | */ |
| 74 | private void calculateAccuracy() { |
| 75 | double delta = upperBound - lowerBound; |
| 76 | accuracy = 1; |
| 77 | while (delta < Math.pow(0.1, accuracy)) { |
| 78 | accuracy++; |
| 79 | if (accuracy > MAXACCURACY) { |
| 80 | break; |
| 81 | } |
| 82 | } |
| 83 | accuracy -= 1; |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Retrieves the accuracy (i.e., number of exact decimal values) of the |
| 88 | * approximation. |
| 89 | * |
| 90 | * @return the accuracy of the approximation |
| 91 | */ |
| 92 | public int getAccuracy() { |
| 93 | return accuracy; |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Retrieves the lower approximation bound after adjustment. |
| 98 | * |
| 99 | * @return the lower approximation bound |
| 100 | */ |
| 101 | public double getAdjustedLowerBound() { |
| 102 | return adjustedLowerBound; |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * Retrieves the upper approximation bound after adjustment. |
| 107 | * |
| 108 | * @return the upper approximation bound |
| 109 | */ |
| 110 | public double getAdjustedUpperBound() { |
| 111 | return adjustedUpperBound; |
| 112 | } |
| 113 | |
| 114 | /** |
| 115 | * Retrieves the lower approximation bound. |
| 116 | * |
| 117 | * @return the lower approximation bound |
| 118 | */ |
| 119 | public double getLowerBound() { |
| 120 | return lowerBound; |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Retrieves the upper approximation bound. |
| 125 | * |
| 126 | * @return the upper approximation bound |
| 127 | */ |
| 128 | public double getUpperBound() { |
| 129 | return upperBound; |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * Checks if the approximation fulfills a required accuracy (i.e., number of |
| 134 | * exact decimal places). |
| 135 | * |
| 136 | * @param requiredAccuracy |
| 137 | * the required accuracy |
| 138 | * @return true if the required accuracy is fulfilled |
| 139 | */ |
| 140 | public boolean hasRequiredAccuracy(final int requiredAccuracy) { |
| 141 | return (accuracy >= requiredAccuracy); |
| 142 | } |
| 143 | } |