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| author | dwinter |
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| date | Tue, 04 Jan 2011 10:02:07 +0100 |
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<HTML> <BODY BGCOLOR="white"> <PRE> <FONT color="green">001</FONT> /*<a name="line.1"></a> <FONT color="green">002</FONT> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a> <FONT color="green">003</FONT> * contributor license agreements. See the NOTICE file distributed with<a name="line.3"></a> <FONT color="green">004</FONT> * this work for additional information regarding copyright ownership.<a name="line.4"></a> <FONT color="green">005</FONT> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a> <FONT color="green">006</FONT> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a> <FONT color="green">007</FONT> * the License. You may obtain a copy of the License at<a name="line.7"></a> <FONT color="green">008</FONT> *<a name="line.8"></a> <FONT color="green">009</FONT> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a> <FONT color="green">010</FONT> *<a name="line.10"></a> <FONT color="green">011</FONT> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a> <FONT color="green">012</FONT> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a> <FONT color="green">013</FONT> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a> <FONT color="green">014</FONT> * See the License for the specific language governing permissions and<a name="line.14"></a> <FONT color="green">015</FONT> * limitations under the License.<a name="line.15"></a> <FONT color="green">016</FONT> */<a name="line.16"></a> <FONT color="green">017</FONT> <a name="line.17"></a> <FONT color="green">018</FONT> package org.apache.commons.math.ode;<a name="line.18"></a> <FONT color="green">019</FONT> <a name="line.19"></a> <FONT color="green">020</FONT> import java.util.ArrayList;<a name="line.20"></a> <FONT color="green">021</FONT> import java.util.List;<a name="line.21"></a> <FONT color="green">022</FONT> import java.io.Serializable;<a name="line.22"></a> <FONT color="green">023</FONT> <a name="line.23"></a> <FONT color="green">024</FONT> import org.apache.commons.math.MathRuntimeException;<a name="line.24"></a> <FONT color="green">025</FONT> import org.apache.commons.math.ode.sampling.StepHandler;<a name="line.25"></a> <FONT color="green">026</FONT> import org.apache.commons.math.ode.sampling.StepInterpolator;<a name="line.26"></a> <FONT color="green">027</FONT> <a name="line.27"></a> <FONT color="green">028</FONT> /**<a name="line.28"></a> <FONT color="green">029</FONT> * This class stores all information provided by an ODE integrator<a name="line.29"></a> <FONT color="green">030</FONT> * during the integration process and build a continuous model of the<a name="line.30"></a> <FONT color="green">031</FONT> * solution from this.<a name="line.31"></a> <FONT color="green">032</FONT> *<a name="line.32"></a> <FONT color="green">033</FONT> * <p>This class act as a step handler from the integrator point of<a name="line.33"></a> <FONT color="green">034</FONT> * view. It is called iteratively during the integration process and<a name="line.34"></a> <FONT color="green">035</FONT> * stores a copy of all steps information in a sorted collection for<a name="line.35"></a> <FONT color="green">036</FONT> * later use. Once the integration process is over, the user can use<a name="line.36"></a> <FONT color="green">037</FONT> * the {@link #setInterpolatedTime setInterpolatedTime} and {@link<a name="line.37"></a> <FONT color="green">038</FONT> * #getInterpolatedState getInterpolatedState} to retrieve this<a name="line.38"></a> <FONT color="green">039</FONT> * information at any time. It is important to wait for the<a name="line.39"></a> <FONT color="green">040</FONT> * integration to be over before attempting to call {@link<a name="line.40"></a> <FONT color="green">041</FONT> * #setInterpolatedTime setInterpolatedTime} because some internal<a name="line.41"></a> <FONT color="green">042</FONT> * variables are set only once the last step has been handled.</p><a name="line.42"></a> <FONT color="green">043</FONT> *<a name="line.43"></a> <FONT color="green">044</FONT> * <p>This is useful for example if the main loop of the user<a name="line.44"></a> <FONT color="green">045</FONT> * application should remain independent from the integration process<a name="line.45"></a> <FONT color="green">046</FONT> * or if one needs to mimic the behaviour of an analytical model<a name="line.46"></a> <FONT color="green">047</FONT> * despite a numerical model is used (i.e. one needs the ability to<a name="line.47"></a> <FONT color="green">048</FONT> * get the model value at any time or to navigate through the<a name="line.48"></a> <FONT color="green">049</FONT> * data).</p><a name="line.49"></a> <FONT color="green">050</FONT> *<a name="line.50"></a> <FONT color="green">051</FONT> * <p>If problem modeling is done with several separate<a name="line.51"></a> <FONT color="green">052</FONT> * integration phases for contiguous intervals, the same<a name="line.52"></a> <FONT color="green">053</FONT> * ContinuousOutputModel can be used as step handler for all<a name="line.53"></a> <FONT color="green">054</FONT> * integration phases as long as they are performed in order and in<a name="line.54"></a> <FONT color="green">055</FONT> * the same direction. As an example, one can extrapolate the<a name="line.55"></a> <FONT color="green">056</FONT> * trajectory of a satellite with one model (i.e. one set of<a name="line.56"></a> <FONT color="green">057</FONT> * differential equations) up to the beginning of a maneuver, use<a name="line.57"></a> <FONT color="green">058</FONT> * another more complex model including thrusters modeling and<a name="line.58"></a> <FONT color="green">059</FONT> * accurate attitude control during the maneuver, and revert to the<a name="line.59"></a> <FONT color="green">060</FONT> * first model after the end of the maneuver. If the same continuous<a name="line.60"></a> <FONT color="green">061</FONT> * output model handles the steps of all integration phases, the user<a name="line.61"></a> <FONT color="green">062</FONT> * do not need to bother when the maneuver begins or ends, he has all<a name="line.62"></a> <FONT color="green">063</FONT> * the data available in a transparent manner.</p><a name="line.63"></a> <FONT color="green">064</FONT> *<a name="line.64"></a> <FONT color="green">065</FONT> * <p>An important feature of this class is that it implements the<a name="line.65"></a> <FONT color="green">066</FONT> * <code>Serializable</code> interface. This means that the result of<a name="line.66"></a> <FONT color="green">067</FONT> * an integration can be serialized and reused later (if stored into a<a name="line.67"></a> <FONT color="green">068</FONT> * persistent medium like a filesystem or a database) or elsewhere (if<a name="line.68"></a> <FONT color="green">069</FONT> * sent to another application). Only the result of the integration is<a name="line.69"></a> <FONT color="green">070</FONT> * stored, there is no reference to the integrated problem by<a name="line.70"></a> <FONT color="green">071</FONT> * itself.</p><a name="line.71"></a> <FONT color="green">072</FONT> *<a name="line.72"></a> <FONT color="green">073</FONT> * <p>One should be aware that the amount of data stored in a<a name="line.73"></a> <FONT color="green">074</FONT> * ContinuousOutputModel instance can be important if the state vector<a name="line.74"></a> <FONT color="green">075</FONT> * is large, if the integration interval is long or if the steps are<a name="line.75"></a> <FONT color="green">076</FONT> * small (which can result from small tolerance settings in {@link<a name="line.76"></a> <FONT color="green">077</FONT> * org.apache.commons.math.ode.nonstiff.AdaptiveStepsizeIntegrator adaptive<a name="line.77"></a> <FONT color="green">078</FONT> * step size integrators}).</p><a name="line.78"></a> <FONT color="green">079</FONT> *<a name="line.79"></a> <FONT color="green">080</FONT> * @see StepHandler<a name="line.80"></a> <FONT color="green">081</FONT> * @see StepInterpolator<a name="line.81"></a> <FONT color="green">082</FONT> * @version $Revision: 811827 $ $Date: 2009-09-06 11:32:50 -0400 (Sun, 06 Sep 2009) $<a name="line.82"></a> <FONT color="green">083</FONT> * @since 1.2<a name="line.83"></a> <FONT color="green">084</FONT> */<a name="line.84"></a> <FONT color="green">085</FONT> <a name="line.85"></a> <FONT color="green">086</FONT> public class ContinuousOutputModel<a name="line.86"></a> <FONT color="green">087</FONT> implements StepHandler, Serializable {<a name="line.87"></a> <FONT color="green">088</FONT> <a name="line.88"></a> <FONT color="green">089</FONT> /** Serializable version identifier */<a name="line.89"></a> <FONT color="green">090</FONT> private static final long serialVersionUID = -1417964919405031606L;<a name="line.90"></a> <FONT color="green">091</FONT> <a name="line.91"></a> <FONT color="green">092</FONT> /** Initial integration time. */<a name="line.92"></a> <FONT color="green">093</FONT> private double initialTime;<a name="line.93"></a> <FONT color="green">094</FONT> <a name="line.94"></a> <FONT color="green">095</FONT> /** Final integration time. */<a name="line.95"></a> <FONT color="green">096</FONT> private double finalTime;<a name="line.96"></a> <FONT color="green">097</FONT> <a name="line.97"></a> <FONT color="green">098</FONT> /** Integration direction indicator. */<a name="line.98"></a> <FONT color="green">099</FONT> private boolean forward;<a name="line.99"></a> <FONT color="green">100</FONT> <a name="line.100"></a> <FONT color="green">101</FONT> /** Current interpolator index. */<a name="line.101"></a> <FONT color="green">102</FONT> private int index;<a name="line.102"></a> <FONT color="green">103</FONT> <a name="line.103"></a> <FONT color="green">104</FONT> /** Steps table. */<a name="line.104"></a> <FONT color="green">105</FONT> private List<StepInterpolator> steps;<a name="line.105"></a> <FONT color="green">106</FONT> <a name="line.106"></a> <FONT color="green">107</FONT> /** Simple constructor.<a name="line.107"></a> <FONT color="green">108</FONT> * Build an empty continuous output model.<a name="line.108"></a> <FONT color="green">109</FONT> */<a name="line.109"></a> <FONT color="green">110</FONT> public ContinuousOutputModel() {<a name="line.110"></a> <FONT color="green">111</FONT> steps = new ArrayList<StepInterpolator>();<a name="line.111"></a> <FONT color="green">112</FONT> reset();<a name="line.112"></a> <FONT color="green">113</FONT> }<a name="line.113"></a> <FONT color="green">114</FONT> <a name="line.114"></a> <FONT color="green">115</FONT> /** Append another model at the end of the instance.<a name="line.115"></a> <FONT color="green">116</FONT> * @param model model to add at the end of the instance<a name="line.116"></a> <FONT color="green">117</FONT> * @exception DerivativeException if some step interpolators from<a name="line.117"></a> <FONT color="green">118</FONT> * the appended model cannot be copied<a name="line.118"></a> <FONT color="green">119</FONT> * @exception IllegalArgumentException if the model to append is not<a name="line.119"></a> <FONT color="green">120</FONT> * compatible with the instance (dimension of the state vector,<a name="line.120"></a> <FONT color="green">121</FONT> * propagation direction, hole between the dates)<a name="line.121"></a> <FONT color="green">122</FONT> */<a name="line.122"></a> <FONT color="green">123</FONT> public void append(final ContinuousOutputModel model)<a name="line.123"></a> <FONT color="green">124</FONT> throws DerivativeException {<a name="line.124"></a> <FONT color="green">125</FONT> <a name="line.125"></a> <FONT color="green">126</FONT> if (model.steps.size() == 0) {<a name="line.126"></a> <FONT color="green">127</FONT> return;<a name="line.127"></a> <FONT color="green">128</FONT> }<a name="line.128"></a> <FONT color="green">129</FONT> <a name="line.129"></a> <FONT color="green">130</FONT> if (steps.size() == 0) {<a name="line.130"></a> <FONT color="green">131</FONT> initialTime = model.initialTime;<a name="line.131"></a> <FONT color="green">132</FONT> forward = model.forward;<a name="line.132"></a> <FONT color="green">133</FONT> } else {<a name="line.133"></a> <FONT color="green">134</FONT> <a name="line.134"></a> <FONT color="green">135</FONT> if (getInterpolatedState().length != model.getInterpolatedState().length) {<a name="line.135"></a> <FONT color="green">136</FONT> throw MathRuntimeException.createIllegalArgumentException(<a name="line.136"></a> <FONT color="green">137</FONT> "dimension mismatch {0} != {1}",<a name="line.137"></a> <FONT color="green">138</FONT> getInterpolatedState().length, model.getInterpolatedState().length);<a name="line.138"></a> <FONT color="green">139</FONT> }<a name="line.139"></a> <FONT color="green">140</FONT> <a name="line.140"></a> <FONT color="green">141</FONT> if (forward ^ model.forward) {<a name="line.141"></a> <FONT color="green">142</FONT> throw MathRuntimeException.createIllegalArgumentException(<a name="line.142"></a> <FONT color="green">143</FONT> "propagation direction mismatch");<a name="line.143"></a> <FONT color="green">144</FONT> }<a name="line.144"></a> <FONT color="green">145</FONT> <a name="line.145"></a> <FONT color="green">146</FONT> final StepInterpolator lastInterpolator = steps.get(index);<a name="line.146"></a> <FONT color="green">147</FONT> final double current = lastInterpolator.getCurrentTime();<a name="line.147"></a> <FONT color="green">148</FONT> final double previous = lastInterpolator.getPreviousTime();<a name="line.148"></a> <FONT color="green">149</FONT> final double step = current - previous;<a name="line.149"></a> <FONT color="green">150</FONT> final double gap = model.getInitialTime() - current;<a name="line.150"></a> <FONT color="green">151</FONT> if (Math.abs(gap) > 1.0e-3 * Math.abs(step)) {<a name="line.151"></a> <FONT color="green">152</FONT> throw MathRuntimeException.createIllegalArgumentException(<a name="line.152"></a> <FONT color="green">153</FONT> "{0} wide hole between models time ranges", Math.abs(gap));<a name="line.153"></a> <FONT color="green">154</FONT> }<a name="line.154"></a> <FONT color="green">155</FONT> <a name="line.155"></a> <FONT color="green">156</FONT> }<a name="line.156"></a> <FONT color="green">157</FONT> <a name="line.157"></a> <FONT color="green">158</FONT> for (StepInterpolator interpolator : model.steps) {<a name="line.158"></a> <FONT color="green">159</FONT> steps.add(interpolator.copy());<a name="line.159"></a> <FONT color="green">160</FONT> }<a name="line.160"></a> <FONT color="green">161</FONT> <a name="line.161"></a> <FONT color="green">162</FONT> index = steps.size() - 1;<a name="line.162"></a> <FONT color="green">163</FONT> finalTime = (steps.get(index)).getCurrentTime();<a name="line.163"></a> <FONT color="green">164</FONT> <a name="line.164"></a> <FONT color="green">165</FONT> }<a name="line.165"></a> <FONT color="green">166</FONT> <a name="line.166"></a> <FONT color="green">167</FONT> /** Determines whether this handler needs dense output.<a name="line.167"></a> <FONT color="green">168</FONT> * <p>The essence of this class is to provide dense output over all<a name="line.168"></a> <FONT color="green">169</FONT> * steps, hence it requires the internal steps to provide themselves<a name="line.169"></a> <FONT color="green">170</FONT> * dense output. The method therefore returns always true.</p><a name="line.170"></a> <FONT color="green">171</FONT> * @return always true<a name="line.171"></a> <FONT color="green">172</FONT> */<a name="line.172"></a> <FONT color="green">173</FONT> public boolean requiresDenseOutput() {<a name="line.173"></a> <FONT color="green">174</FONT> return true;<a name="line.174"></a> <FONT color="green">175</FONT> }<a name="line.175"></a> <FONT color="green">176</FONT> <a name="line.176"></a> <FONT color="green">177</FONT> /** Reset the step handler.<a name="line.177"></a> <FONT color="green">178</FONT> * Initialize the internal data as required before the first step is<a name="line.178"></a> <FONT color="green">179</FONT> * handled.<a name="line.179"></a> <FONT color="green">180</FONT> */<a name="line.180"></a> <FONT color="green">181</FONT> public void reset() {<a name="line.181"></a> <FONT color="green">182</FONT> initialTime = Double.NaN;<a name="line.182"></a> <FONT color="green">183</FONT> finalTime = Double.NaN;<a name="line.183"></a> <FONT color="green">184</FONT> forward = true;<a name="line.184"></a> <FONT color="green">185</FONT> index = 0;<a name="line.185"></a> <FONT color="green">186</FONT> steps.clear();<a name="line.186"></a> <FONT color="green">187</FONT> }<a name="line.187"></a> <FONT color="green">188</FONT> <a name="line.188"></a> <FONT color="green">189</FONT> /** Handle the last accepted step.<a name="line.189"></a> <FONT color="green">190</FONT> * A copy of the information provided by the last step is stored in<a name="line.190"></a> <FONT color="green">191</FONT> * the instance for later use.<a name="line.191"></a> <FONT color="green">192</FONT> * @param interpolator interpolator for the last accepted step.<a name="line.192"></a> <FONT color="green">193</FONT> * @param isLast true if the step is the last one<a name="line.193"></a> <FONT color="green">194</FONT> * @throws DerivativeException this exception is propagated to the<a name="line.194"></a> <FONT color="green">195</FONT> * caller if the underlying user function triggers one<a name="line.195"></a> <FONT color="green">196</FONT> */<a name="line.196"></a> <FONT color="green">197</FONT> public void handleStep(final StepInterpolator interpolator, final boolean isLast)<a name="line.197"></a> <FONT color="green">198</FONT> throws DerivativeException {<a name="line.198"></a> <FONT color="green">199</FONT> <a name="line.199"></a> <FONT color="green">200</FONT> if (steps.size() == 0) {<a name="line.200"></a> <FONT color="green">201</FONT> initialTime = interpolator.getPreviousTime();<a name="line.201"></a> <FONT color="green">202</FONT> forward = interpolator.isForward();<a name="line.202"></a> <FONT color="green">203</FONT> }<a name="line.203"></a> <FONT color="green">204</FONT> <a name="line.204"></a> <FONT color="green">205</FONT> steps.add(interpolator.copy());<a name="line.205"></a> <FONT color="green">206</FONT> <a name="line.206"></a> <FONT color="green">207</FONT> if (isLast) {<a name="line.207"></a> <FONT color="green">208</FONT> finalTime = interpolator.getCurrentTime();<a name="line.208"></a> <FONT color="green">209</FONT> index = steps.size() - 1;<a name="line.209"></a> <FONT color="green">210</FONT> }<a name="line.210"></a> <FONT color="green">211</FONT> <a name="line.211"></a> <FONT color="green">212</FONT> }<a name="line.212"></a> <FONT color="green">213</FONT> <a name="line.213"></a> <FONT color="green">214</FONT> /**<a name="line.214"></a> <FONT color="green">215</FONT> * Get the initial integration time.<a name="line.215"></a> <FONT color="green">216</FONT> * @return initial integration time<a name="line.216"></a> <FONT color="green">217</FONT> */<a name="line.217"></a> <FONT color="green">218</FONT> public double getInitialTime() {<a name="line.218"></a> <FONT color="green">219</FONT> return initialTime;<a name="line.219"></a> <FONT color="green">220</FONT> }<a name="line.220"></a> <FONT color="green">221</FONT> <a name="line.221"></a> <FONT color="green">222</FONT> /**<a name="line.222"></a> <FONT color="green">223</FONT> * Get the final integration time.<a name="line.223"></a> <FONT color="green">224</FONT> * @return final integration time<a name="line.224"></a> <FONT color="green">225</FONT> */<a name="line.225"></a> <FONT color="green">226</FONT> public double getFinalTime() {<a name="line.226"></a> <FONT color="green">227</FONT> return finalTime;<a name="line.227"></a> <FONT color="green">228</FONT> }<a name="line.228"></a> <FONT color="green">229</FONT> <a name="line.229"></a> <FONT color="green">230</FONT> /**<a name="line.230"></a> <FONT color="green">231</FONT> * Get the time of the interpolated point.<a name="line.231"></a> <FONT color="green">232</FONT> * If {@link #setInterpolatedTime} has not been called, it returns<a name="line.232"></a> <FONT color="green">233</FONT> * the final integration time.<a name="line.233"></a> <FONT color="green">234</FONT> * @return interpolation point time<a name="line.234"></a> <FONT color="green">235</FONT> */<a name="line.235"></a> <FONT color="green">236</FONT> public double getInterpolatedTime() {<a name="line.236"></a> <FONT color="green">237</FONT> return steps.get(index).getInterpolatedTime();<a name="line.237"></a> <FONT color="green">238</FONT> }<a name="line.238"></a> <FONT color="green">239</FONT> <a name="line.239"></a> <FONT color="green">240</FONT> /** Set the time of the interpolated point.<a name="line.240"></a> <FONT color="green">241</FONT> * <p>This method should <strong>not</strong> be called before the<a name="line.241"></a> <FONT color="green">242</FONT> * integration is over because some internal variables are set only<a name="line.242"></a> <FONT color="green">243</FONT> * once the last step has been handled.</p><a name="line.243"></a> <FONT color="green">244</FONT> * <p>Setting the time outside of the integration interval is now<a name="line.244"></a> <FONT color="green">245</FONT> * allowed (it was not allowed up to version 5.9 of Mantissa), but<a name="line.245"></a> <FONT color="green">246</FONT> * should be used with care since the accuracy of the interpolator<a name="line.246"></a> <FONT color="green">247</FONT> * will probably be very poor far from this interval. This allowance<a name="line.247"></a> <FONT color="green">248</FONT> * has been added to simplify implementation of search algorithms<a name="line.248"></a> <FONT color="green">249</FONT> * near the interval endpoints.</p><a name="line.249"></a> <FONT color="green">250</FONT> * @param time time of the interpolated point<a name="line.250"></a> <FONT color="green">251</FONT> */<a name="line.251"></a> <FONT color="green">252</FONT> public void setInterpolatedTime(final double time) {<a name="line.252"></a> <FONT color="green">253</FONT> <a name="line.253"></a> <FONT color="green">254</FONT> // initialize the search with the complete steps table<a name="line.254"></a> <FONT color="green">255</FONT> int iMin = 0;<a name="line.255"></a> <FONT color="green">256</FONT> final StepInterpolator sMin = steps.get(iMin);<a name="line.256"></a> <FONT color="green">257</FONT> double tMin = 0.5 * (sMin.getPreviousTime() + sMin.getCurrentTime());<a name="line.257"></a> <FONT color="green">258</FONT> <a name="line.258"></a> <FONT color="green">259</FONT> int iMax = steps.size() - 1;<a name="line.259"></a> <FONT color="green">260</FONT> final StepInterpolator sMax = steps.get(iMax);<a name="line.260"></a> <FONT color="green">261</FONT> double tMax = 0.5 * (sMax.getPreviousTime() + sMax.getCurrentTime());<a name="line.261"></a> <FONT color="green">262</FONT> <a name="line.262"></a> <FONT color="green">263</FONT> // handle points outside of the integration interval<a name="line.263"></a> <FONT color="green">264</FONT> // or in the first and last step<a name="line.264"></a> <FONT color="green">265</FONT> if (locatePoint(time, sMin) <= 0) {<a name="line.265"></a> <FONT color="green">266</FONT> index = iMin;<a name="line.266"></a> <FONT color="green">267</FONT> sMin.setInterpolatedTime(time);<a name="line.267"></a> <FONT color="green">268</FONT> return;<a name="line.268"></a> <FONT color="green">269</FONT> }<a name="line.269"></a> <FONT color="green">270</FONT> if (locatePoint(time, sMax) >= 0) {<a name="line.270"></a> <FONT color="green">271</FONT> index = iMax;<a name="line.271"></a> <FONT color="green">272</FONT> sMax.setInterpolatedTime(time);<a name="line.272"></a> <FONT color="green">273</FONT> return;<a name="line.273"></a> <FONT color="green">274</FONT> }<a name="line.274"></a> <FONT color="green">275</FONT> <a name="line.275"></a> <FONT color="green">276</FONT> // reduction of the table slice size<a name="line.276"></a> <FONT color="green">277</FONT> while (iMax - iMin > 5) {<a name="line.277"></a> <FONT color="green">278</FONT> <a name="line.278"></a> <FONT color="green">279</FONT> // use the last estimated index as the splitting index<a name="line.279"></a> <FONT color="green">280</FONT> final StepInterpolator si = steps.get(index);<a name="line.280"></a> <FONT color="green">281</FONT> final int location = locatePoint(time, si);<a name="line.281"></a> <FONT color="green">282</FONT> if (location < 0) {<a name="line.282"></a> <FONT color="green">283</FONT> iMax = index;<a name="line.283"></a> <FONT color="green">284</FONT> tMax = 0.5 * (si.getPreviousTime() + si.getCurrentTime());<a name="line.284"></a> <FONT color="green">285</FONT> } else if (location > 0) {<a name="line.285"></a> <FONT color="green">286</FONT> iMin = index;<a name="line.286"></a> <FONT color="green">287</FONT> tMin = 0.5 * (si.getPreviousTime() + si.getCurrentTime());<a name="line.287"></a> <FONT color="green">288</FONT> } else {<a name="line.288"></a> <FONT color="green">289</FONT> // we have found the target step, no need to continue searching<a name="line.289"></a> <FONT color="green">290</FONT> si.setInterpolatedTime(time);<a name="line.290"></a> <FONT color="green">291</FONT> return;<a name="line.291"></a> <FONT color="green">292</FONT> }<a name="line.292"></a> <FONT color="green">293</FONT> <a name="line.293"></a> <FONT color="green">294</FONT> // compute a new estimate of the index in the reduced table slice<a name="line.294"></a> <FONT color="green">295</FONT> final int iMed = (iMin + iMax) / 2;<a name="line.295"></a> <FONT color="green">296</FONT> final StepInterpolator sMed = steps.get(iMed);<a name="line.296"></a> <FONT color="green">297</FONT> final double tMed = 0.5 * (sMed.getPreviousTime() + sMed.getCurrentTime());<a name="line.297"></a> <FONT color="green">298</FONT> <a name="line.298"></a> <FONT color="green">299</FONT> if ((Math.abs(tMed - tMin) < 1e-6) || (Math.abs(tMax - tMed) < 1e-6)) {<a name="line.299"></a> <FONT color="green">300</FONT> // too close to the bounds, we estimate using a simple dichotomy<a name="line.300"></a> <FONT color="green">301</FONT> index = iMed;<a name="line.301"></a> <FONT color="green">302</FONT> } else {<a name="line.302"></a> <FONT color="green">303</FONT> // estimate the index using a reverse quadratic polynom<a name="line.303"></a> <FONT color="green">304</FONT> // (reverse means we have i = P(t), thus allowing to simply<a name="line.304"></a> <FONT color="green">305</FONT> // compute index = P(time) rather than solving a quadratic equation)<a name="line.305"></a> <FONT color="green">306</FONT> final double d12 = tMax - tMed;<a name="line.306"></a> <FONT color="green">307</FONT> final double d23 = tMed - tMin;<a name="line.307"></a> <FONT color="green">308</FONT> final double d13 = tMax - tMin;<a name="line.308"></a> <FONT color="green">309</FONT> final double dt1 = time - tMax;<a name="line.309"></a> <FONT color="green">310</FONT> final double dt2 = time - tMed;<a name="line.310"></a> <FONT color="green">311</FONT> final double dt3 = time - tMin;<a name="line.311"></a> <FONT color="green">312</FONT> final double iLagrange = ((dt2 * dt3 * d23) * iMax -<a name="line.312"></a> <FONT color="green">313</FONT> (dt1 * dt3 * d13) * iMed +<a name="line.313"></a> <FONT color="green">314</FONT> (dt1 * dt2 * d12) * iMin) /<a name="line.314"></a> <FONT color="green">315</FONT> (d12 * d23 * d13);<a name="line.315"></a> <FONT color="green">316</FONT> index = (int) Math.rint(iLagrange);<a name="line.316"></a> <FONT color="green">317</FONT> }<a name="line.317"></a> <FONT color="green">318</FONT> <a name="line.318"></a> <FONT color="green">319</FONT> // force the next size reduction to be at least one tenth<a name="line.319"></a> <FONT color="green">320</FONT> final int low = Math.max(iMin + 1, (9 * iMin + iMax) / 10);<a name="line.320"></a> <FONT color="green">321</FONT> final int high = Math.min(iMax - 1, (iMin + 9 * iMax) / 10);<a name="line.321"></a> <FONT color="green">322</FONT> if (index < low) {<a name="line.322"></a> <FONT color="green">323</FONT> index = low;<a name="line.323"></a> <FONT color="green">324</FONT> } else if (index > high) {<a name="line.324"></a> <FONT color="green">325</FONT> index = high;<a name="line.325"></a> <FONT color="green">326</FONT> }<a name="line.326"></a> <FONT color="green">327</FONT> <a name="line.327"></a> <FONT color="green">328</FONT> }<a name="line.328"></a> <FONT color="green">329</FONT> <a name="line.329"></a> <FONT color="green">330</FONT> // now the table slice is very small, we perform an iterative search<a name="line.330"></a> <FONT color="green">331</FONT> index = iMin;<a name="line.331"></a> <FONT color="green">332</FONT> while ((index <= iMax) && (locatePoint(time, steps.get(index)) > 0)) {<a name="line.332"></a> <FONT color="green">333</FONT> ++index;<a name="line.333"></a> <FONT color="green">334</FONT> }<a name="line.334"></a> <FONT color="green">335</FONT> <a name="line.335"></a> <FONT color="green">336</FONT> steps.get(index).setInterpolatedTime(time);<a name="line.336"></a> <FONT color="green">337</FONT> <a name="line.337"></a> <FONT color="green">338</FONT> }<a name="line.338"></a> <FONT color="green">339</FONT> <a name="line.339"></a> <FONT color="green">340</FONT> /**<a name="line.340"></a> <FONT color="green">341</FONT> * Get the state vector of the interpolated point.<a name="line.341"></a> <FONT color="green">342</FONT> * @return state vector at time {@link #getInterpolatedTime}<a name="line.342"></a> <FONT color="green">343</FONT> * @throws DerivativeException if this call induces an automatic<a name="line.343"></a> <FONT color="green">344</FONT> * step finalization that throws one<a name="line.344"></a> <FONT color="green">345</FONT> */<a name="line.345"></a> <FONT color="green">346</FONT> public double[] getInterpolatedState() throws DerivativeException {<a name="line.346"></a> <FONT color="green">347</FONT> return steps.get(index).getInterpolatedState();<a name="line.347"></a> <FONT color="green">348</FONT> }<a name="line.348"></a> <FONT color="green">349</FONT> <a name="line.349"></a> <FONT color="green">350</FONT> /** Compare a step interval and a double.<a name="line.350"></a> <FONT color="green">351</FONT> * @param time point to locate<a name="line.351"></a> <FONT color="green">352</FONT> * @param interval step interval<a name="line.352"></a> <FONT color="green">353</FONT> * @return -1 if the double is before the interval, 0 if it is in<a name="line.353"></a> <FONT color="green">354</FONT> * the interval, and +1 if it is after the interval, according to<a name="line.354"></a> <FONT color="green">355</FONT> * the interval direction<a name="line.355"></a> <FONT color="green">356</FONT> */<a name="line.356"></a> <FONT color="green">357</FONT> private int locatePoint(final double time, final StepInterpolator interval) {<a name="line.357"></a> <FONT color="green">358</FONT> if (forward) {<a name="line.358"></a> <FONT color="green">359</FONT> if (time < interval.getPreviousTime()) {<a name="line.359"></a> <FONT color="green">360</FONT> return -1;<a name="line.360"></a> <FONT color="green">361</FONT> } else if (time > interval.getCurrentTime()) {<a name="line.361"></a> <FONT color="green">362</FONT> return +1;<a name="line.362"></a> <FONT color="green">363</FONT> } else {<a name="line.363"></a> <FONT color="green">364</FONT> return 0;<a name="line.364"></a> <FONT color="green">365</FONT> }<a name="line.365"></a> <FONT color="green">366</FONT> }<a name="line.366"></a> <FONT color="green">367</FONT> if (time > interval.getPreviousTime()) {<a name="line.367"></a> <FONT color="green">368</FONT> return -1;<a name="line.368"></a> <FONT color="green">369</FONT> } else if (time < interval.getCurrentTime()) {<a name="line.369"></a> <FONT color="green">370</FONT> return +1;<a name="line.370"></a> <FONT color="green">371</FONT> } else {<a name="line.371"></a> <FONT color="green">372</FONT> return 0;<a name="line.372"></a> <FONT color="green">373</FONT> }<a name="line.373"></a> <FONT color="green">374</FONT> }<a name="line.374"></a> <FONT color="green">375</FONT> <a name="line.375"></a> <FONT color="green">376</FONT> }<a name="line.376"></a> </PRE> </BODY> </HTML>