Matrix operations

Hi Everybody,

Is it possible to carry out matrix operations in Alisp/Vlisp (say 50x50)?. If not is it possible to import such a thing from excel as a table and then access individual values (elements) in the table?.

This is for some engineering calculations involving finite element analysis (as a hobby).

Thanks in advance.

Have a look at these links

http://stackoverflow.com/questions/11449657/writing-a-simple-matrix-class-in-common-lisp-for-practice

http://phase.hpcc.jp/mirrors/stat/sapaclisp/matrix.lisp

http://rosettacode.org/wiki/Matrix_multiplication

http://common-lisp.net/project/lisplab/

They are for common LISP and I'm not sure if they will work in LISP or VLISP.

Thanks Tyke. I like to do it in Alisp as it is easier to do the design of the structure and draw it with a macro. Therefore common-lisp will not do.

Not sure what the limits are on a list but you can attemp to create a 50x50 "Matrix" as a list then you can get any row/column by using nth in a double loop. In my old R12 lisp book there is a specific section on matrix's so maybe check Help as well. You could also use a table as well similar method of row/column to retrieve data

;row 25 col 32
(setq val (nth 32 (nth 25 mylist)))

;a 3x3 
(setq mylist (((1 2 3)(4 5 6)(7 8 9))((1 2 3)(4 5 6)(7 8 9))((1 2 3)(4 5 6)(7 8 9))))

Thanks Bigal, I believe this a way of representing three matrices, each a 3x3 one. Is there an easy way to access each item, say 2nd row (i) and third column (j) of a matrix we can assign it to variable K23 ( or Kij) and use it elsewhere ?.

Re read my post i put an example (setq k23 (nth 2 (nth 3 mylist)))

I am using 2013 and it takes your list with a quote ('). However (setq k23 (nth 2 (nth 3 mylist))) gives an error.

My version has a 'vlax-safearray-put-element' and '......-get-element' functionality which can construct and then extract elements one at a time from a matrix. I believe it is more useful than excel which is limited to 52x52 at present ?. I am not trying something that contains slabs and beams with several hundreds elements at this time (like the expensive commercial software); an 80x80 matrix would do.

The mylist is an example would need to make a list of lists your correct it will give errors

(setq mylist (list (list (list 1 2 3)(list 4 5 6)(list 7 8 9))(list (list 1 2 3)(list 4 5 6)(list 7 8 9))(list (list 1 2 3)(list 4 5 6)(list 7 8 9))))
;oops forgot nth starts at 0
(setq k23 (nth 1 (nth 2 mylist))) ; returns ( 4 5 6)

Yes, it works Bigal. Thanks. I will try safearrays too and come back later. I have uploaded some files showing samples. Unfortunately I could not upload the last two which shows the adding of all elements to one single matrix called global matrix. I have given the link to a video from a commercial software in this regard.

IMG_0001.pdf

IMG_0002.pdf

IMG_0003.pdf

BIGAL,

This is a belated reply.

I have realized that there are a large number of software written in Fortran and these can be run via ObjectARX in AutoCAD if one were to make use of them to design something (say a multiple box culvert) and draw the sections etc. I already have hundreds of them (f95& f03)that do the matrix multiplication (up to million by million matrices) process data and form stiffness matrix etc required in structural calculations. I have given some samples above. So, I believe the best option is to make use of ObjectARX facility.

Thanks for replying.

Aloy