brian abraham

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13 years, 283 days

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These are questions asked by brian abraham

This is an error message when using printlevel with the RKF45 solver Many thanks
I have two equations with 3 variables(or perhaps n equations with n+1 variables) eq1:=0=c1*A1+c2*B1+c3*C1; eq2:=0=c4*A1+c5*B1+c6*C1; I can solve by e.g. solve({eq1,eq2},{A1,B1}) or any other combination of two of the variables. But if I follow the above by solve({eq1,eq2},{B1,C1}) I get then get an error. How do I find C1 as a function of A1? There must surely be a very way simple to do this. Did check the help pages but must have missed it if it is there.
I am using dsolve(numeric,number=12,procedure=solproc,start=0,initial=ic,procvars=dvars,output=Vector(50, (i -> i/10.))): to solve for position from a set of motion equation and it works very nicely. Is there any way to end the dsolve procedure before all the time steps have been calculated if a specified variable is less than a specified value? I know I could run dsolve to find the time at which the variable has the specified value and then rerun with the specified time value but calculation times are lengthy so I don't want to double the time.
I have four column vectors of data points; X1,Y1,X2,Y2 (n=30) where pointA is given by (X1[n],Y1[n]) and pointB by (X2[n],Y2[n]) I can plot lines using indvidual rows with n=rownumber plot([ [X1[n],Y1[n]],[X2[n],Y2[n]] ]) However, I want to animate the plot so it shows n=1, then n=2 and etc. I am aware of the "insequence" option but I don't want to have to write the 30 entries into a "display" command. Any tips
I have four column vectors of data points; X1,Y1,X2,Y2 (n=30) where point1 is given by (X1[n],Y1[n]) and point2 by (X2[n],Y2[n]) I can plot lines using indvidual rows with n=rownumber plot([ [X1[n],Y1[n]],[X2[n],Y2[n]] ]) However, I want to animate the plot so it shows n=1, then n=2 and etc. I am aware of the "insequence" option but I don't want to have to write the 30 entries into a "display" command. Any tips
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