Joe Riel

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20 years, 4 days

MaplePrimes Activity


These are replies submitted by Joe Riel

@Carl Love I included the explicit assignment because the code was confusing enough with it.  Anyhow, in a rewrite of the Iterator package I'm providing a nicer way to extract the output Array to avoid the call to ModuleIterator. That is, one would be able to do

M := ArrayTools:-Alias(Output(P), [m,n]):

The reason no call to g() is needed in the loop is that the call to g only returns the Vector used as the output. Because this Vector is updated in-place, its address never changes.  This is why the iterator is efficient in memory usage, and why ArrayTools:-Alias works. The Vector is updated when the hasNext (h) function is called, which is done automatically by the do loop.

 



@quann169 $include works fine if it is inside a file read by Maple, either command line Maple or the GUI.  That is, in the GUI, you can issue the command

read "somefile.mpl";

and if it has an include statement it will be handled.

@acer Agreed, that would simplify things.  In the meantime, a corrected version of the Iterator package is now available at the Maplesoft Application Center. The mla and help have been tested on Maple 16, 17, and 18 (thanks Preben).

@Thomas Richard Nice tip,Thomas.  Guess I don't look at the status bar much; I never noticed that the current directory is listed there and can be changed by clicking on it.  

@acer A clarification.  The "parsing error" you mentioned is a difference between what the user expects and what Maple interprets.  No error is raised.

@Preben Alsholm Apologies. I see that that the mla in the distributed 2.3.4 release is empty. Apparently my Make file needs some tweaking. Also, I didn't distribute the help file. I've updated the Makefile to include the help, however, am currently have a problem rebuilding the hdb (for use with Maple 17).  Should get it straightened out shortly. Today is a holiday, so the earliest the new zip file will be available is tomorrow. I'll post here when it is available (version 2.3.5).

Note that I've been slowly rewriting the Iterator package to make each Iterator more object oriented. This makes it easier to parallelize each Iterator. I plan to parallelize the BinarGrayCode iterator next, that will allow a faster solution to this problem.

@liushunyi Did you install the Iterator package?  It is available in the Maplesoft Application Center.

@Preben Alsholm Maple 18's new help system uses *.help files for its help database, not *.hdb. I thought I included a *.help file with the Iterator package on the Application Center. If not, let me know and I'll be sure to update the package.

This doesn't explain why with(Iterator) fails. What error message do you get?

@Alejandro Jakubi Using Maple 18's help search input from the worksheet in the Standard GUI, Physics,diff shows up as the fourth suggestion, which is reasonable.  Adding it to the See Also section in diff seems useful.

@Preben Alsholm You can do slighty better by eliminating the assignment to B and assigning prod as

prod := (-1)^s*mul(add(M[i,j],j=T),i=1..m);

 

@nm No good reason. I couldn't immediately recall which package provided the extension to diff that allowed that, so used frontend because it is familar.

@Bendesarts Causal signals are distinct from acausal signals in that they are designated as either inputs or outputs (technically the port is designated as such, not the signal).  All boolean and integer signals are causal. The physical domain ports (electrical, thermal, multibody, etc) are all acausal real signals.  The output of a sensor attached to an acausal signal is causal.   Most acausal ports consist of a through-variable and an across-variable.  The through-variable (also known as a flow-variable) models the flow of some quantity, (e.g. current in an electrical port). The across-variable models the potential (e.g voltage in an electrical port).

@Bendesarts It depends on the port and the system.  Doing so can lead to an insoluble system of equations. Some ports, say causal outputs, can always be left open. 

The error messages references R4 and S4, neither of which I see in the portion of the model that is visible.  Does the R8, the revolute below the one you are driving, have a non-zero spring constant or damping coeffiicent?  If not, there would be no opposing torque, so simulation would be invalid.

@nic_rf Attach mass (Multibody > Bodies and Frames > Rigid Body to the right side of the force transducer and to left side of the rigid body attached to the transducer.

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