@Carl Love 

I have another question. Is simplify command exact? for example, in the file I have attached, when u execute M2 to see the result, the output is too lengthy, while using simplify(M2) it reduces dramatically. Can I trust on the simplify command???

@Carl Love 

Dear Carl Love, I have uploaded my file. I used the command you mentioned, but it doesn't work. The small numbers remain unchanged. As you can see for M1ff variable, the numbers such as 1.6e-11 and so on still exist.

P1dprime_(3).mw

@Carl Love 

How can I use this command?

At the beginning of the worksheet or at the beginning of every command that I execute?

My second question is that how can I specify the numbers of digits to be ignord by Maple?

e.g. I want maple to consider 1e-7 as zero but 1e-6 remains unchanged at output,

@Preben Alsholm 

Thanks dear Preben Alsholm. you are right. I made changes you mentioned. The problem resolved. Thanks again.

The modified mw file has uploaded.

P2.mw

@tomleslie 

I'm sorry for the problem that occured.

The modified mw file has been uploaded.

@Carl Love 

Actually, I'm not sure about the source of error, I think so. Maybe the problem is due to another issue.

I want to know the source of error to resolve it.

@tomleslie 

Thanks so much dear tomleslie for your guid.

@tomleslie 

Dear tomleslie. I want actually to differentiate wrt to Xn(t) components in the file. I think the problem of being zero for all components of the C matrix using the methods mentioned by you is when I construct the M1 matrix, it consists of components depending on Xn(t) components like x(t), theta(t), etc. But, when I call M1(1,7) for example, Maple returns B₁₃(1,1) and differentiating this term yields zero, while when calling B₁₃(1,1), Maple returns its real value depending on Xn(t) components and differentiating wrt to Xn(t) does not yield zero. Please see the modified file. I did applied what I said.

Diff.mw

@Carl Love and @tomleslie 

I want to construct a large matrix from a recursive formula using 'for loop'. An error message appears when I use 'diff' command for differentiation. Would you help me in this case too, please? I have attached the corresponding file.

Diff.mw

@tomleslie 

Thanks for your guid. I did not type all of that input. I derived the relations in another file and copied them to this attached file. As I mentioned, my relations are too long and handling them is too hard. For example, I tried to copy "C45", it took a long time to select it and unfortunately it did not copied and I coudn't paste it in another file.

@Carl Love 

Thanks Carl for your good tips. I thought that using 'I' with subscript or superscript is permissible and make no mistake for Maple. I have to change it from the source. Thank you again dear Carl 

@Carl Love 

Thanks so much Carl Love for your help. My problem solved with your guide. My last question is that why should I change the first term (Q^%T . `#mi("M")` . `#mi("Q")`) to Q^%T.M.Q. Why it cannot remain unchanged like other terms in 1-D math input format?

@tomleslie 

SymmetryCheck.mw

@Carl Love 

I uploaded a file containing a small part of my relations. The matrices are all symbolic. The problem solved by the proposed solution of tomleslie. But another problem appeared while checking the symmetry of the whole matrix. Maybe this error appears because of lengthy formula.