Problems plotting with linspace

Greetings. In particular, having several plots together using different vector lengths does not allow me to change the font, line colour, special character etc of the successive plots. Instead for the code below, it displays a strange rainbow colour line for the vertical plots y1 and y2. My question is, how to change the font, line colour, line width of plots y1 and y2?

x = linspace(-4, 3, 100);

a = ((5+x).^(0.5));

b = ((3/2).^((-7*x)/6));

ExpCurve = exp((x.^2).^0.5)+a.*b;

a1 = ((5-3.5).^(0.5));

b1 = ((3/2).^((-7*(-3.5))/6));
XL = exp(((-3.5).^2).^0.5)+a1.*b1;

y1 = linspace(0, XL, 40);

a2 = ((5+2.5).^(0.5));
b2 = ((3/2).^((-7*(2.5))/6));
XR = exp(((2.5).^2).^0.5)+a2.*b2;

y2 = linspace(0, XR, 40);

plot(x, ExpCurve, -3.5, y1, 2.5, y2, 'LineWidth', 2)

xlabel('x' , 'FontSize', 20)

ylabel('y' , 'FontSize', 20)

Answer 1

[Walter Roberson]

handles = plot(x, ExpCurve, -3.5, y1, 2.5, y2, 'LineWidth', 2);
set(handles(2), 'color', 'r', 'linewidth', 7)
set(handles(3), 'color', [.8 .1 .3], 'linewidth', 2)

[Kurt Lee]

The above response does not fix the problem. The code still generates the rainbow coloured vertical plots for y1 and y2.

[Walter Roberson]

You must be using an older MATLAB version; R2014b and later would not generate visible lines at all.

MATLAB has a rule for plotting that if X is a vector of length N, and Y is N x M then M lines will be plotted, as if by plot(X, Y(:,1), X, Y(:,2), X, Y(:,3) ... X, Y(:,N). Furthermore for convenience, if X is a vector of length N and Y is M x N (M ~= N) then Y will be internally transposed and then the one-line-per-column rule would be used.

You are using a scalar X, -3.5, with a vector y, y1. A scalar is 1 x 1, the row vector is 1 x M, so this fits the above situation with N = 1 -- 1 x N for X, N x M for Y, so M lines are being plotted, one for each column of Y, so one for each element of the vector y1. Switching to y1.' would not help because of the helpful automatic transpose.

Your corrected plot command would be

plot(x, ExpCurve, [-3.5 -3.5], [0 XL], [2.5 2.5], [0 XR], 'LineWidth', 2)