String scalar or character vector must have valid interpreter syntax

axis ([0,20,0,20])

text(3.0, 8.0,'\fontsize{30} \omega=2 \pi*f=2 \pi*c/ \lamda')

[Nicolás Bozzo]

the letter is called lambda not lamda

[Walter Roberson]

@Nicolás Bozzo

In Modern Greek, the name of the letter is Λάμδα

https://en.wikipedia.org/wiki/Lambda#Character_encodings

Unicode uses the (Modern Greek-based) spelling "lamda" in character names, instead of "lambda", due to "the pre-existing names in ISO 8859-7, as well as preferences expressed by the Greek National Body".[18]

Answer 1

[Ameer Hamza]

Here are two options to write this

axis ([0,20,0,20])
text(3.0, 8.0,'$\omega=2 \pi*f=2 \pi*c /\lambda$', ...
    'Interpreter', 'latex', ...
    'FontSize', 30)

and

axis ([0,20,0,20])
text(3.0, 8.0,'\omega=2 \pi*f=2 \pi*c /\lambda', ...
    'Interpreter', 'tex', ...
    'FontSize', 30)

Read more about intrepreter options here: https://www.mathworks.com/help/matlab/ref/text.html#f68-481090_sep_shared-Interpreter

[George Rodriguez]

Thank you so much!

[Ameer Hamza]

I am glad to be of help!!!

[George Rodriguez]

I try to emulate what you did for another code but my subscripts and superscripts do not appear. Can you tell me what am i doing wrong?

text(2,2, '\ y_{z} = e^{2} = 1+ x+ x^{2}/2!+ \x^{3}/3+',...

'Interpreter', 'tex', ...

'FontSize', 20)

thank you again.

[Ameer Hamza]

You placed escape character (\) at unnecessary locations

text(2,2, 'y_{z} = e^{2} = 1+ x+ x^{2}/2!+ x^{3}/3+',...
    'Interpreter', 'tex', ...
    'FontSize', 20)

[George Rodriguez]

Oh, you use it only for special charaters I see, thank you again!