<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt;color:#000000;"><DIV>Hi,</DIV>
<DIV> </DIV>
<DIV>I wonder if the "rkf" method uses a fixed number of intermediate times as said here <A href="http://math.fullerton.edu/mathews/n2003/RungeKuttaFehlbergMod.html">http://math.fullerton.edu/mathews/n2003/RungeKuttaFehlbergMod.html</A>.</DIV>
<DIV> </DIV>
<DIV>For example, if I define a function F:</DIV>
<DIV>--</DIV>
<DIV>function Xdot=F(t,X)<BR><BR> //printf("t=%f \n",t)<BR> <BR> Xdot = ... ;<BR> <BR>endfunction;</DIV>
<DIV>--</DIV>
<DIV>and make a first integration:</DIV>
<DIV>--</DIV>
<DIV>pas_temps = 0.001;<BR>t0 = 170*pas_temps;<BR>tf = 180*pas_temps;<BR><BR>X0 = ... ;<BR><BR>Trajectoire1 = ode("rkf",X0,t0,t0:pas_temps:tf,F);</DIV>
<DIV>--</DIV>
<DIV>and a second integration beginning with the result obtained at time t=0.178 (for example):</DIV>
<DIV>--</DIV>
<DIV>t0 = 178*pas_temps;<BR>tf = 180*pas_temps;<BR><BR>X0 = Trajectoire1(:,9);<BR><BR>Trajectoire2 = ode("rkf",X0,t0,t0:pas_temps:tf,F);</DIV>
<DIV>--</DIV>
<DIV>then is Trajectoire2 supposed to be the same as Trajectoire1(:,9:11)?</DIV>
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<DIV>Because I have an example that gives different results and found (by using printf("t=%f \n",t)) that the number of intermediate times changed from one integration to another.</DIV>
<DIV> </DIV>
<DIV>Thank you in advance for your help. I'm really stuck.</DIV></div><br>
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