Activity for Marc
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Marc posted a comment on ticket #65
Perfect, thank you!
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Or first a follow-up question, still in the file coco/po/examples/hopf/demo.m, where I have added following lines to plot po_run: figure(2); clf; thm = struct('special', {{'EP'}}); coco_plot_bd(thm, 'po_run', 'p1', 'p2', '||x||_{2,MPD}') When po_run has been calculated with 'bifus', 'off', the plotting function gives following error: Error using coco_bd_col>coco_get_col coco_bd_col: column not found: 'po.test.USTAB' Error in coco_bd_col (line 32) col = coco_get_col(bd, name, cat_flag); Error in coco_plot_bd...
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Hi Thanks for confirming the syntax. A quick test with coco/po/examples/hopf/demo.m confirmed that order matters. prob = coco_prob(); %prob = coco_set(prob, 'po', 'bifus', 'off'); %test 1: OK prob = ode_HB2po(prob, '', 'ep_run', HBlab); %prob = coco_set(prob, 'po', 'bifus', 'off'); %test 2: too late fprintf(... '\n Run=''%s'': Continue periodic orbits from point %d in run ''%s''.\n', ... 'po_run', HBlab, 'ep_run'); bd3 = coco(prob, 'po_run', [], 1, 'p1', [-1 1]); The error was that I tried to add...
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*all po constructors
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Disable detection of bifurcations
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Perfect! This question can be closed.
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Got it! It seems to be function y = marc(data, xbp, ~, ~, p)
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Hello Harry Thank you. I now have understood how to use a bddat function during the continuation run to store quantities of interest to be used during the plotting, and am adapting your example above. For this, I also need to access the current parameter values inside the bddat function. I checked the content of data.coll_seg but did not find this, although data.coll_seg.maps has the field pdim (dimension of parameter vector). Related to your comments above, I suppose that the parameter vector p...
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It seems that the asterisk is interpreted as italic text. I mean position x = x1 . phi1 + x2 . phi2 abs(phi1 . MAX(x(1,:)) + phi2 . MAX(x(3,:))) abs(MAX(phi1 . x(1,:) + phi2 . x(3,:)))
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Dear Harry Thank you. For the practical case of a SDOF system with state (position x, velocity v), and where we only consider the values that were calculated during continuation, your following suggestion : coco_plot_bd('po_run', 'p1', 'p2', {'MAX(x)' 'MIN(x)'}, @(x,y) abs(x(1,:)-y(1,:))); and coco_plot_bd('po_run', 'p1', 'p2', {'MAX(x)' 'MIN(x)'}, @(x,y) abs(x(2,:)-y(2,:))); enables to plot the maximum amplitude of the position (resp. velocity). I have a follow-up question: how to handle a 2-DOF...
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Just to make your question clearer: a MX error is raised at STEP -1, indeed. Furthermore, there is a Warning: Matrix is singular to working precision.
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Just to make your question clearer: a MX error is raised at STEP -1, indeed. Furthermore, there is a Warning: Matrix is singular to working precision.
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Just to make your question clearer: a MXerror is raised at STEP -1, indeed. Furthermore, there is a Warning: Matrix is singular to working precision.
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Thank you for the information. I was confused. I finally understood how to use ode_PD2po with success in order to find the period-doubling branch between two PDs. This question can be closed.
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I was confused. I finally understood how to use ode_PD2po with success in order to find the period-doubling branch between two PDs. This question can be closed.
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Thank you for this detailed information. I have not yet understood the syntax when using ep_add_bddat and po_add_bddat (for instance, why the argument d in the example of svds in your first answer above)? Very practically speaking, I have calculated the continuation of a vector field as function of (position x, speed xdot). I now would like to draw the bifurcation diagram using * either abs(max(x)-min(x)) * or abs(max(xdot)-min(xdot)) as amplitude. When using po_add_bddat, how to indicate to use...
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Thank you for this detailed information. I have not yet understood the syntax when using ep_add_bddat and po_add_bddat (for instance, why the argument d in the example of svds in your first answer above)? Very practically speaking, I have calculated the continuation of a vector field as function of (position x, speed xdot). I now would like to draw the bifurcation diagram using * either abs(max(x)-min(x)) * or abs(max(xdot)-min(xdot)) as amplitude. When using po_add_bddat, how to indicate to use...
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Hello Harry Thanks for your comments. In any case, if plotting would become too slow because too many data files have to be accessed, one can find in fact easy workarounds such as extracting the relevant data and storing them in another form (.mat/.fig/...) to speed up manipulation in Matlab. This question can therefore be closed. Best regards Marc
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How to set perturbation in ode_PD2po
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Hello I am following e.g. SN points as function of two parameters, for a quite stiff system. In some cases, even when setting a large maximum step size, and a minimum step size of 1E-16, the chosen step size gradually becomes smaller, so many points are calculated. 1. Sometimes, this works fine: you just have to wait long enough. 2. Sometimes, COCO gets stuck at the minimal step size of 1E-16, when the Newton algorithm is not converging (even having increased ItMX from 20 to say, 100). Stopping and...
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coco_plot_bd many points
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Hello Harry This works perfectly, thank you!! Marc
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Hello, thank you for your answer. I could not find a coding error so far. However, I was able to reproduce the error by modifing the file demo.m in the tor folder. 1. PD %% Continuation of period-doubling bifurcations PDlabs = coco_bd_labs(bd2, 'PD'); prob = coco_prob(); prob = coco_set(prob, 'cont', 'NAdapt', 5); bd4 = coco(prob, 'pd1', 'ode', 'PD', 'PD', ... 'po2', PDlabs(1), {'nu' 'po.period' 'be'}, [-0.65, -0.55]); %addendum prob2 = coco_prob(); prob2 = coco_set(prob2, 'cont', 'NAdapt', 5, 'ItMX',...
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Error when following TR
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Additional parameters : prob = coco_set(prob, ’cont’, ’NAdapt’, 1); adaptive setting of the Atlas algorithm (see [PO-Tutorial.pdf, p. 5])
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Different continuation fails and what to do
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Amplitude definitions
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Thank you!
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Hopf bifurcation continuation with 1 parameter only
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