symbolic calculation with nested arrays

[pprestininzi]

Hi all,

i once used to write on Mathcad Collab forum.

here is my question:

with reference to the .mcd file attached, how can i use nested arrays for symbolic calculation?

thanks

[AndyWesterman]

HI ,

Is this what you are wanting to achieve?

Regards

Andy

[pprestininzi]

hi, thanks for the quick reply,

can you please post your worksheet in mcd 2001 version?

thanks

Edit sorry for the multiple post: the system kept on saying that the failed to send the reply....i managed to delete the multiple posts.

[AndyWesterman]

Hi,

I'm sorry but Mathcad 15 only saves as far back as ver 11.

All I can do is attach a picure.

regards

Andy

[pprestininzi]

i can't replicate the loop you defined, don't know what that right pointing arrow means.

please find attached what i was able to achieve (preatty much nothing to be honest)

[AndyWesterman]

Hi,

Right pointing arrow was the symbolic calculation arrow , but it seems to work equally well either way in Mathcad15.

Your sheet is giving :

do you get the same result?

Regards

Andy

[pprestininzi]

did you just open my sheet?

in mathcad 2001, E(x,y)-> results in "no symbolic result was found"

strangely the E function is well defined, as if i try to evaluate it like E(2,1) it correctly results in (0,2,1,-2,-1,3,1,-3,1)

[AndyWesterman]

Very odd.

I just opened the sheet as I downloaded it from the PTC website& that's the answer it gave.

Since it can evaluate a numeric result it obviously has saved a version of the symbolic answer, just that it doesn't want to display it.

Unfortunately I don't have any way to try in a lower version so you will need an expert for the 2001i revision.

Regards

Andy

[pprestininzi]

i have to thank you for your time!

let's wait for someone who can help us!

[RichardJ]

Here is the file in 2001 format.

[pprestininzi]

hi richard, thanks for converting the file to mcd 2001: however it stil doesn't work: moreover with your file (with the definition containing the right pointing arrow) even the definition turns red...

strange things going on eh?

[RichardJ]

Things have changed over the years. It works in version 11. I guess something was changed in either version 2001i or version 11. What is the error message when it turns red?

[pprestininzi]

i managed to take a screenshot with the error displayed: notice the correct evaluation of E(-1,-1)

[RichardJ]

It may just be that in version 2000 the symbolic engine does not understand programs.

[pprestininzi]

if you check the very first mcd file that i posted it had the same problem even without programming.

[RichardJ]

There are many reasons the symbolic processor may not be able to find a solution. The reasons in the two files may not be the same.

[RichardJ]

Does this work in 2000?

[pprestininzi]

hi Richard,

1) what do you mean with TWO files?

2) no, your last sheet doesn't work: both e_7*f(x,y)-> and e_i*f(x,y)-> turn red ("no symbolic result was found").

3) i'm using mathcad 2001 professional.

Can we now state the problem is related to nested arrays?

[RichardJ]

By two files I mean the file I posted and the file you posted.

The only thing we can state is that the symbolic processor in verson 2000 does not understand the syntax. What happens if you replace e with a vector of 1's?

[pprestininzi]

it works just fine: see attached image.

[RichardJ]

In which case it does look like the symbolic processor in version 2000 can't handle nested arrays.

[pprestininzi]

strange that nobody had bumped into this before...i don't know if i have to feel unlucky or proud....

thanks everybody for the support....once back home (in a couple of months) i will try in mcd14 which i have purchased but forgot home...

[RichardJ]

You are using a version of Mathcad that's more than 10 years old. All of these examples work in later versions (certainly version 11 and later, and 11 came out only a couple of years after 2000). Many people may have seen this before. It's just that we have forgotten it

[LucMeekes]

I checked behaviour in Mcad 2000.

The symbolic processor is not completely unhappy with a nested array: e-> will show the nested array as being a nested array, although the nesting cannot be expanded. (I use '->' here for symbolic evaluation.)

But what the symbolic processor does not understand is indexing in a nested array: e[0-> results in 'No symbolic result was found'.

I defined a (simple, unnested) array f with two elements, and the symbolic processor is happy to show the result of f[0->.

I assume Mcad2001 does the same.

Success!

Luc

[pprestininzi]

LucMeekes ha scritto:

The symbolic processor is not completely unhappy with a nested array: e-> will show the nested array as being a nested array

that's not what's happening in mcd 2001: even e-> results into "no symbolic result was found.".

[LucMeekes]

Pietro,

sorry, my assumption is proven worthless by you. Apparently Mcad2000 is better than 2001...?

Luc

[pprestininzi]

Apparently...yes. this is even stranger...

[RichardJ]

Which service pack are you running? The last service pack for 2001 was service pack 2.

[pprestininzi]

Richard Jackson ha scritto:

Which service pack are you running? The last service pack for 2001 was service pack 2.

how do i check it?

[RichardJ]

Go to "help", "about". It should tell you there.