@Carl Love thank you for your solution! I will have a closer look later on.

@Carl Love thank you for your solution and the additional comment on return. All this information helps to get bit by bit better acquainted with Maple

@tomleslie Thank you for your help. The reason why they look the same is because the pH values in this example are very small which is not always the case in my data. Everything is now clear to me I was not aware that I had to add return.

@tomleslie Thank you for your help. I have been able to obtain the correct results now in the attached worksheet but I still have 2 issues:

1. How can I transform this to a procedure

2. How can I obtain the results for P50 and Pcor in a matrix?

Once again thank you for your time and help.Proc_example.mw

@tomleslie 

First thank you for your prompt answer. Second, my apologies but the procedure is only part of what I want to achieve and that is the reason why there are 3 parameters and the quantity S which are used in the full procedure. I am trying to get more experience with Maple by slowly transferring my Mathcad sheets to Maple. Maybe it will help you when I show the 'procedure' how it was in Mathcad: 

but as my in between result for P50 is wrong I removed part of it. As always you help, insight and "little tricks" are appreciated.

@Samir Khan Thank you for showing me this alternative method. I appreciate your commitment.

@mmcdara thank you for your workaround. I worked previously with mathcad where it was possible to fit with units. Your solution is a bit more cumbersome but at least it is a solution. Thanks again.

@acer Thank you I wanted indeed a plain vector.

@tomleslie thank you so much! My mistake was that I did not add parenthesis ("(") before Data and after "BFH". Have a nice evening.

@tomleslie thank you for your help. I really appreciate your commitment to help out people having questions/issues while trying to master maple!

@vv Thank you for your solutions to my questions. However, I still have an issue with my second question. If I want to take the mean of the first column, I get Float(undefined). Could you help me out once more? Thanks in advance.
 

Download Questions.mwQuestions.mw

@acer  Thank you for your solution(s). I am slowly transitioning from a software with less symbolic capabilities, and apparently I need to digest a lot more before I will be able to use Maple efficiently. 

@tomleslie thank you for your informative answer. As a newbie to Maple I still have a lot to learn.

Thank you both for your answers!

@acer

Thank you all for your additional comments and remarks as they help me in slowly ameliorating my Maple knowledge.