Writing to file in for loop in MathCAD Prime 9.0

[RA_10945383]

Hi all,

I have a MathCAD Prime worksheet to calculate a 2-d matrix called HL which itself is indexed with j. I need to calculate this matrix for j:=2..207 and I want each of these matrices to be saved to a comma separated .text file with a different name. I have figured out how, for a given value of j, I can save the file that I want, but I could not figure out how to do all this in a loop. I need a loop, or another way of doing this, so that I can save all those 206 files automatically. Many thanks for your help!

Roman

[MartinHanak]

Hi,

please upload your mcdx file.

[RA_10945383]

Dear Martin,

thanks for your interest to help. I have attached my MathCAD file in my reply to Luc. Does this allow you to offer a solution that would work for me? Many thanks!

Roman

[MartinHanak]

[RA_10945383]

Dear Martin,

many thanks for offering a solution too! I have not tried it yet, but many thanks!

Roman

[LucMeekes]

This little program

Creates n files: The line

M<-matrix...

Creates an n by n matrix with sequential numbers in the rows and columns starting at i

The line

fil <- concat....

Creates a filename containing the number i

And the line

WRITECSV...

Writes out the matrix to the file

Called with:

ït creates 3 matrices, the first contains:

1,2,3

2,2,3

3,3,3

The second contains:

2,3,4

3,3,4

4,4,4

And the third contains:

3,4,5

4,4,5

5,5,5

Success!
Luc

[RA_10945383]

Dear Luc,

thanks for sharing your little program! This is helpful, I learned something already, but I failed to adapt it to my script and make it work. I attach my MathCAD worksheet here. Unfortunately I'm not able to share with the data, but you can see how I calculate the matrix, followed by a manual workaround for printing to file. How would I adapt my script to print each of the i:2..207 matrices to file?

Thanks,

Roman

[Werner_E · Accepted solution]

See if this does the job

[RA_10945383]

Dear Werner,

this works! Thank you so much!

I don't fully understand why it works, but I suspect it has to do with how you defined r as element x, and c element y. I had not seen this used before and don't know what difference it makes to defining r as element 1..8 for example. If you have time to briefly explain or link to an explanation I would be very happy to learn. Oddly, when the script is done, it circles Animal_j in red and says "this value must be a string", but this doesn't matter because the job isdone already.

Kind regards,

Roman

[Werner_E]

What a range variable like x or y is in the worksheet, is a for loop in a program.
Actually a range can be seen as an implicit for-loop - its not a vector (which often is cause for confusion).

I simply wanted to use the ranges x and y you already had defined and so I used variable names r and c (I was thinking of "row" and "column" to cycle through x and y. Otherwise the program just does what you showed for j=2 and for general j in your sheet.

Without using the already defines worksheet ranges x and y you could use the very same names in the program and use these names as (local) variables in the for-loops:

Now it may be more obvious that these nested for-loops create the very same matrix HL for each value of j as you had shown in the worksheet using the (now obsolete) range variables x and y. These ranges are not needed anymore and can be deleted.

According the error message you get I can only guess and speculate due to the lack of the actual data.
Best guess is that the vector "Animal" has more than 207 elements and that element #208 is not a string like the entries before.

If that's the case, you could use the constant "207" as the last value of the j-loop instead of "last(Animal)" (as can be seen in code snippet above).