I am trying to overload the "." operator (noncommutative product) to handle objects I have implemented as records. Each record contains a matrix R and a parameter l. A.B will produce a new record where l is l_A+l_B and R is R_A.R_B, "." here being the normal matrix product (and I use LinearAlgebra:-Multiply in the body of my procedure for this). The objects A and B are of type 'Element', which I have defined (using AddType) and which works.

I implemented the procedure...

So I have this array of plots with log vertical axes. I generate it with a seq(logplot(.....)) construct and then display the whole sequence. Works like a charm...except all plots have linear scale! So I try plot(...,axis[2]=[mode=log]): works fine for direct plot but not in display. I try to add the log axis to display, like display(...axis[2]=[mode=log]): same result, linear axes.

Is plots:-display unable to produce a log plot? I can obviously plot the log(data),...

acer discussed in a recent post the effect of different array types on performance.

I have, however, a much more elementary question: Maple has a bewildering number of differing data structures: Arrays, Vectors, lists, sets, tables,... Some of these are supersets of others.

Being still on the learning curve I am building a module with definitions of certain functions or procedures I use frequently, such as to make my life easier. A lot of my stuff uses array-like...

I have a 4 by 4 matrix that I need to augment to a 7 by 7 matrix.

I find I can use the "|" operator to append a column to my original matrix. So I can do this three times and I have a 4 by 7 matrix.

Now, the only way I have found to add the three rows I still need to add is to transpose, use "|" three times and to transpose back. While this indeed works it is rather clumsy and probably not efficient.

Is there a better way to do that better; i.e. is there...

I am writing a module that will have several procedures. This module will be loaded using "with(modulename)."

Inside one of the procedures (a procedure dealing with opening a data file) I am testing for the existence of a file and, if it does not exist, it should open a filedialog so I can navigate to the relevant folder that has the file. Like this (test is set from the existence-checker to be true or false):

if (not test) then # have to get and set currentdir