Too many non-property/value arguments error occurred when applying a text box to a figure

Here is the line:

text(2,3,'\bf fontname{times} infty','FontSize',12,'center')

Answer 1

[Walter Roberson]

'center' is not an option by itself. You want either 'HorizontalAlignment', 'center' or 'VerticalAlignment', 'center'

Also you appear to be missing \ before fontname and before infty: '\bf \fontname{times} \infty'

[Zeynab Mousavikhamene]

Thanks for your note. what is the role of \?

I uesed 'HorizontalAlignment', 'center' but the inf is not in the middle. For example I need inf sign to be exactly in the middle of x=2 (highlighted in the picture).

[Walter Roberson]

text(2, 3, '\bf\fontname{times}\infty','horizontalalignment', 'center', 'fontsize', 12)

That is, those two spaces you had in your control string were being output as spaces.

\ signals to the (default) tex interpreter that the next few characters are a command or special character . For example 'beta \beta' would output