xlabel not visible on plot

[Lukas Reichlin]

Dear Octave Community,

How can I make xlabel('Frequency [rad/s]') visible on a plot? The plot  
window seems to be too small. I'm using Octave 3.2.0 on Mac OS X  
10.5.7 with GnuPlot 4.2.5 and AquaTerm 1.0.1. Thanks for any help.

Regards,
Lukas


EXAMPLE M-FILE:


% Heat Exchanger


% Tabula Rasa
clear all;
close all;
clc;


% Physical Parameters
m_star_1 = 0.5;  % kg/s
m_star_2 = 0.2;  % kg/s
V_1 = 0.01;      % m^3
V_2 = 0.02;      % m^3

rho = 1000;      % kg/m^3
c = 4200;        % J/(kg K)
Ar = 2;          % m^2
k = 2000;        % W/(m^2 K)


% Control-Oriented Parameters
tau_1 = rho * V_1 * c / ( m_star_1 * c  +  k * Ar );
tau_2 = rho * V_2 * c / ( m_star_2 * c  +  k * Ar );

sigma_1 = k * Ar / ( m_star_1 * c  +  k * Ar );
sigma_2 = k * Ar / ( m_star_2 * c  +  k * Ar );

beta_1 = m_star_1 * c / ( m_star_1 * c  +  k * Ar );
beta_2 = m_star_2 * c / ( m_star_2 * c  +  k * Ar );


% System Matrices
A = [      -1/tau_1    sigma_1/tau_1 ;
      sigma_2/tau_2         -1/tau_2 ];

B = [ beta_1/tau_1               0 ;
                 0    beta_2/tau_2 ];

C = [ 1    0 ;
      0    1 ];

D = [ 0    0 ;
      0    0 ];


% State Space Form
sys = ss(A,B,C,D);


% Stability
eigw = eig(A)


% Controllability
co = ctrb(A,B);
r_co = rank(co)


% Observability
ob = obsv(A,C);
r_ob = rank(ob)


% Singular Value Plot
w = logspace(-3, 1, 1000);   % rad/s

for k = 1 : size(w, 2)
        
        % Frequency Response Matrix
        P = C * inv(i * w(k) * eye(size(A))  -  A) * B  +  D;
        
        % Singular Value Decomposition
        sigma = svd(P);
        sigma_max(k) = max(sigma);
        sigma_min(k) = min(sigma);
end

figure(1)
semilogx(w, 20*log10(sigma_max), w, 20*log10(sigma_min))
xlabel('Frequency [rad/s]')
ylabel('Singular Values [dB]')
grid on