whats wrong with this code?

I have a while loop as shown in the attached file and all these variables

nr_zones_analyzed,

combinations_of_salts, vekt_prosent_best_salt_1,

vekt_prosent_best_salt_2,

samlet_vannaktivitet

,Osmotic_pressure

Are set within the loop

The code relevant for the error that occurred is included in the file.

I get the following error saying:

Conversion to double from cell is not possible.

The error points to this line:

Osmotisk_data(nr_zones_analyzed,:)={nr_zones_analyzed, combinations_of_salts, vekt_prosent_best_salt_1,vekt_prosent_best_salt_2, samlet_vannaktivitet,Osmotic_pressure}

And it occurs when I have run the code for antall_soner = 2.

Can anybody tell me whats wrong with this code..? :)

Answer 1

[Image Analyst]

I didn't look at your code but from the sounds of it you're probably trying to do this with your cell array

dbl = str2double(ca(1));

when you should be using braces to get the contents of the cell, like this:

dlb = str2double(ca{1});

See the FAQ:

https://matlab.fandom.com/wiki/FAQ#What_is_a_cell_array?

It will tell you when to use parentheses, braces, or brackets.

[Muazma Ali]

@Image Analyst I am sorry but I really cant see where I did such thing , can you please elaborate by looking at my code..? :)

[Image Analyst]

Give me code that runs

Unrecognized function or variable 'beregn_osmotisk_trykk'.

Also it asks for many inputs. What are the values you entered?

[Muazma Ali]

@Image Analyst you can overlook it as I am doing a little easier for the reader and having it as an input in the file attached..

[Image Analyst]

No I cannot overlook (ignore) the fact that the "beregn_osmotisk_trykk" function is missing. Your code won't run without it. You must give it to us if you want our help.

Also I think you overlooked my request for the inputs that should be entered, because you did not tell us any of them. What numbers do we tell your program?

Answer 2

[Walter Roberson]

varType=["double", "double", "double", "double", "double", "string"];

varNames=["Zone_nr", "Combinations_of_salts", "Weight_percent_best_salt_1", "Weight_percent_best_salt_2", "Total_water_activity", "Osmotic_pressure"];

So Combination_of_salts must be a double.

 C(nr_zones_analyzed, 1)=string(best_salt_1)+ ' ' + string(best_salt_2);

Entries in C are string

 combinations_of_salts=C;

So combinations_of_salts is string array.

 Osmotisk_data(nr_zones_analyzed,:)={nr_zones_analyzed, combinations_of_salts, vekt_prosent_best_salt_1,vekt_prosent_best_salt_2, samlet_vannaktivitet,Osmotic_pressure}

combinations_of_salts is being sent to the second column of the table, and the second column of the table must be double, but the source is string array.

[Muazma Ali]

@Walter Roberson Hi ! Thanks I just edited the code but then I got a strange error message saying:

'' Element 1 must be convertible to a string

scalar.''

I am attaching the edited file

[Walter Roberson]

 C(nr_zones_analyzed, 1)=string(best_salt_1)+ ' ' + string(best_salt_2);

each iteration of the loop, you are expanding C.

 combinations_of_salts=C;

That includes all current entries in C. Second iteration of the loop it would be a 2 x 1 string array for example.

Osmotisk_data(nr_zones_analyzed,:)={nr_zones_analyzed, combinations_of_salts, vekt_prosent_best_salt_1,vekt_prosent_best_salt_2, samlet_vannaktivitet,Osmotic_pressure}

You try to import that multi-entry combinations_of_salts as a string scalar into the table.

What you should be doing is

combinations_of_salts = C(nr_zones_analyzed,1);

[Muazma Ali]

@Walter Roberson thanks a lot !

I just want to be sure that I understood it correctly ; since it is just one colum you chose to write it this way..?

[Walter Roberson]

@Muazma Ali

The first iteration, your combinations_of_salts=C; would be trying to store one string element in the second column, and that would succeed.

The second iteration, your combinations_of_salts=C would be referring to the C that had grown to two rows of strings, so

Osmotisk_data(nr_zones_analyzed,:)={nr_zones_analyzed, combinations_of_salts, vekt_prosent_best_salt_1,vekt_prosent_best_salt_2, samlet_vannaktivitet,Osmotic_pressure}

would be trying to store a string array with two rows into the one table output row. But when you specify "string" for the variable type, that expects exactly one string per row, not a string array with two or more rows, so it fails.

You do not want to be storing the entire accumulated C array as you go. You do not want

1 ... "abc" ...

2 ... ["abc"; "def"] ...

3 ... {"abc"; "def"; "ghi"] ...

You just want

1 ... "abc" ...

2 ... "def" ...

3 ... "ghi" ...

So your combinations_of_salts should, at any time, only reflect the new information to be added to the table, not all of the accumulated information.

[Muazma Ali]

@Walter Roberson It worked for some time then I got same error message when I ran my own program.

And if I run this file attached which is a shorter version of my prog, I dont get anything out for combinations of salts field.. :(

Please help me with my problem