Mathcad: differentiating with indexes

[Uku]

Hello!

The picture says a thousand words:
http://www.hot.ee/jaaniussikesed/v6rrand.jpg

In the last member under the square root, there is the error. For some reason I am not able to differentiate with an array index, t_s1 is a single column 5 row matrix. How to solve this? The error says "a name is required here".

Thanks,
U.

 

[NemoReally]

Hello!

The picture says a thousand words:
http://www.hot.ee/jaaniussikesed/v6rrand.jpg

In the last member under the square root, there is the error. For some reason I am not able to differentiate with an array index, t_s1 is a single column 5 row matrix. How to solve this? The error says "a name is required here".

Thanks,
U.

Try assigning ts1[i to a variable, t say, and differentiate that instead.