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root/OpenMD/branches/development/src/math/CubicSpline.cpp
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Comparing branches/development/src/math/CubicSpline.cpp (file contents):
Revision 1849 by gezelter, Wed Feb 20 13:52:51 2013 UTC vs.
Revision 1877 by gezelter, Thu Jun 6 15:43:35 2013 UTC

# Line 35 | Line 35
35   *                                                                      
36   * [1]  Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).            
37   * [2]  Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).          
38 < * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 24107 (2008).          
38 > * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).          
39   * [4]  Kuang & Gezelter,  J. Chem. Phys. 133, 164101 (2010).
40   * [5]  Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
41   */
# Line 188 | Line 188 | void CubicSpline::generate() {
188    return;
189   }
190  
191 < RealType CubicSpline::getValueAt(RealType t) {
191 > RealType CubicSpline::getValueAt(const RealType& t) {
192    // Evaluate the spline at t using coefficients
193    //
194    // Input parameters
# Line 198 | Line 198 | RealType CubicSpline::getValueAt(RealType t) {
198    
199    if (!generated) generate();
200    
201 <  assert(t < data_.front().first);
202 <  assert(t > data_.back().first);
201 >  assert(t > data_.front().first);
202 >  assert(t < data_.back().first);
203  
204    //  Find the interval ( x[j], x[j+1] ) that contains or is nearest
205    //  to t.
# Line 227 | Line 227 | RealType CubicSpline::getValueAt(RealType t) {
227   }
228  
229  
230 < pair<RealType, RealType> CubicSpline::getValueAndDerivativeAt(RealType t) {
230 > void CubicSpline::getValueAt(const RealType& t, RealType& v) {
231 >  // Evaluate the spline at t using coefficients
232 >  //
233 >  // Input parameters
234 >  //   t = point where spline is to be evaluated.
235 >  // Output:
236 >  //   value of spline at t.
237 >  
238 >  if (!generated) generate();
239 >  
240 >  assert(t > data_.front().first);
241 >  assert(t < data_.back().first);
242 >
243 >  //  Find the interval ( x[j], x[j+1] ) that contains or is nearest
244 >  //  to t.
245 >
246 >  if (isUniform) {    
247 >    
248 >    j = max(0, min(n-1, int((t - data_[0].first) * dx)));  
249 >
250 >  } else {
251 >
252 >    j = n-1;
253 >    
254 >    for (int i = 0; i < n; i++) {
255 >      if ( t < data_[i].first ) {
256 >        j = i-1;
257 >        break;
258 >      }      
259 >    }
260 >  }
261 >  
262 >  //  Evaluate the cubic polynomial.
263 >  
264 >  dt = t - data_[j].first;
265 >  v = data_[j].second + dt*(b[j] + dt*(c[j] + dt*d[j]));  
266 > }
267 >
268 >
269 > pair<RealType, RealType> CubicSpline::getValueAndDerivativeAt(const RealType& t){
270    // Evaluate the spline and first derivative at t using coefficients
271    //
272    // Input parameters
# Line 237 | Line 276 | pair<RealType, RealType> CubicSpline::getValueAndDeriv
276  
277    if (!generated) generate();
278    
279 <  assert(t < data_.front().first);
280 <  assert(t > data_.back().first);
279 >  assert(t > data_.front().first);
280 >  assert(t < data_.back().first);
281  
282    //  Find the interval ( x[j], x[j+1] ) that contains or is nearest
283    //  to t.
# Line 264 | Line 303 | pair<RealType, RealType> CubicSpline::getValueAndDeriv
303    dt = t - data_[j].first;
304  
305    yval = data_[j].second + dt*(b[j] + dt*(c[j] + dt*d[j]));
306 <  dydx = b[j] + dt*(2.0 * c[j] + 3.0 * dt * d[j]);
307 <  
306 >  dydx = b[j] + dt*(2.0 * c[j] + 3.0 * dt * d[j]);
307 >
308    return make_pair(yval, dydx);
309   }
310 +
311 + void CubicSpline::getValueAndDerivativeAt(const RealType& t, RealType& v,
312 +                                          RealType &dv) {
313 +  // Evaluate the spline and first derivative at t using coefficients
314 +  //
315 +  // Input parameters
316 +  //   t = point where spline is to be evaluated.
317 +
318 +  if (!generated) generate();
319 +  
320 +  assert(t > data_.front().first);
321 +  assert(t < data_.back().first);
322 +
323 +  //  Find the interval ( x[j], x[j+1] ) that contains or is nearest
324 +  //  to t.
325 +
326 +  if (isUniform) {    
327 +    
328 +    j = max(0, min(n-1, int((t - data_[0].first) * dx)));  
329 +
330 +  } else {
331 +
332 +    j = n-1;
333 +    
334 +    for (int i = 0; i < n; i++) {
335 +      if ( t < data_[i].first ) {
336 +        j = i-1;
337 +        break;
338 +      }      
339 +    }
340 +  }
341 +  
342 +  //  Evaluate the cubic polynomial.
343 +  
344 +  dt = t - data_[j].first;
345 +
346 +  v = data_[j].second + dt*(b[j] + dt*(c[j] + dt*d[j]));
347 +  dv = b[j] + dt*(2.0 * c[j] + 3.0 * dt * d[j]);
348 + }

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