MaplePrimes - answers and comments on Question, Adding column headings to output file fprintf

possibility

Joe Riel — Thu, 15 Oct 2009 10:06:44 Z

Here's one approach,

proc()
local dsys, data, w;
    dsys := {diff(v(t),t) = -x(t), diff(x(t),t)=v(t), x(0)=1, v(0)=0};
    data := dsolve(dsys, 'numeric', 'output'=Array([seq(0..2, 0.1)]));
    w := 15;
    printf("%*s\n", w,  map(convert, data[1,1], string));
    printf("%*f\n", w, data[2,1]);
end proc():
              t            v(t)            x(t)
       0.000000        0.000000        1.000000
       0.100000       -0.099833        0.995004
       0.200000       -0.198669        0.980067
       0.300000       -0.295520        0.955336
       0.400000       -0.389418        0.921061
       0.500000       -0.479426        0.877583
       0.600000       -0.564643        0.825336
       0.700000       -0.644218        0.764842
       0.800000       -0.717356        0.696707
       0.900000       -0.783327        0.621610
       1.000000       -0.841471        0.540302
       1.100000       -0.891207        0.453596
       1.200000       -0.932039        0.362358
       1.300000       -0.963558        0.267499
       1.400000       -0.985450        0.169967
       1.500000       -0.997495        0.070737
       1.600000       -0.999574       -0.029200
       1.700000       -0.991665       -0.128844
       1.800000       -0.973848       -0.227202
       1.900000       -0.946300       -0.323290
       2.000000       -0.909298       -0.416147

As a bous, with Maple13 you can use convert~(data[1,1], string) to convert the elements in the Vector stored in data[1,1] to a string. A slightly more interesting method is to assign an inline operator for convert and then use it with the ~ operator:

`&c` := convert:
data[1,1] &c~ string;

There really should be a

alex_01 — Thu, 15 Oct 2009 15:37:09 Z

There really should be a predefined and simple procedure for that in Maple for example

MatrixPrint( Column1, Column2, Column3, labels=["A", "AA", "AAA"]

The current Maple command :

for i to 10 do printf("\t%d\t%2d\t%3d\t%4d\t%5d\t%6d\ \n", i^1, i^2, i^3, i^4, i^5, i^6) end do;

In my opinion is too complicated ///*&..;;££%%%>>\\££"" what langauge is that ?! Greek ?

using Matrix to present table of results

Doug Meade — Thu, 15 Oct 2009 21:05:31 Z

I achieve this result using Maple's Matrix data structure, as follows:

interface( rtablesize=30 ):
dsys := {diff(v(t),t) = -x(t), diff(x(t),t)=v(t), x(0)=1, v(0)=0};
data := dsolve(dsys, 'numeric', 'output'=Array([seq(0..2, 0.1)]));
evalf[6]( < data[1,1], data[2,1] > );

All this does is create a matrix from the two elements returned by dsolve. Note that it's necessary to increase the setting of rtablesize if the matrix has more than 10 rows or columns; here, 30 is more than enough.

If only there was a way to copy this result into MaplePrimes.

Doug

---------------------------------------------------------------------
Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Thanks

archstevej — Wed, 11 Nov 2009 03:32:41 Z

Thanks for this discussion.

printf

alec — Fri, 16 Oct 2009 17:04:37 Z

It is also possible to write the printf commands as

printf("%{}15a\n%15f",data[1,1],data[2]);
              t            v(t)            x(t)
       0.000000        0.000000        1.000000
       0.100000       -0.099833        0.995004

Alec

nice

Joe Riel — Fri, 16 Oct 2009 19:10:32 Z

Thanks. I was pretty sure there was a way to "map" %a over an rtable, but didn't think of using an empty printf_rtable modifier. Nifty. That is

printf("%{}a\n", some_rtable)

is roughly equivalent to

printf("%s\n", map(convert, some_rtable, string));