Text as input for function

Hi, I need tot write a function 'tjirp' that takes an input 'linear' (so the text). If I do so, I get a parse error saying it's invalid MATLAB syntax. What am I missing?

function [x,info]=tjirp(t,f, 'lineair');
if t > 1
    msg = 't moet kleiner zijn dan 1';
    error(msg)
end 
if 'lineair' == 'kwadratisch'
    x = cos(2*pi*f*t.^3/3);
else 
    x = cos(2*pi*f*t.^2/2);
end
t = 0: 0.1:1;
plot(t, x)
title('Plot van cosinus')
xlabel('tijd')

if f>50
    info = fprintf ('samplefrequentie is groot genoeg');
else 
    info = fprintf ('samplefrequentie is te klein');
end 
end 

Answer 1

[Ameer Hamza]

When defining a function, you need to write the name of a variable

function [x,info]=tjirp(t,f, str)

Also change the line

if str == 'kwadratisch'

You can pass the value value when calling the function

tjirp(2,1,'linear') % for example