Extract all columns from a table where the column names "start with" a string

How can I extract all columns from a table where the column names "start with" a string?

For example, in

mytable = array2table(NaN(4,5));
mytable.Properties.VariableNames = {'A1', 'A2', 'B1', 'F2', 'F4'};

How would I extract all the "F*" columns in to a new table?

Answer 1

[Walter Roberson]

mask = startsWith( mytable.Properties.VariableNames, 'F');
Fcols = mytable(:,mask);

[newbie9]

thanks so much

Answer 2

[Arnaud Delorme]

colNames = fieldnames(mytable);

[~,inds] = intersect(colNames, { 'A1' 'A2' } );

mytable = mytable(:,sort(inds));

[Walter Roberson]

This would not get you anything that mytable(:, { 'A1' 'A2' } ) would not give, other than preserving relative order of variables.