Adding a second x-axis to the top

Hello dear altruist,

in need of help here. I need to add a second x-axis to the top of my graph here:

The x-axis values at the top is just the inverse of the variable below (2*pi/kx). This would help me visualize the data both in terms of wavevector and wavelength. The codes and files are attached herwith. Thanks in advance.

clc; clear all;
load infinite;
% transpose matrix is not required
A1= log10(fs1);
kx=ky;
h1=figure
p1=pcolor(kx*1e-6,f/1e12,A1);
xlabel('\it{k_x} (\rm{\times10^6 m^{-1}})') ;ylabel('{\itf} (THz)');
ylim([33 1600]);
set(h1, 'Units', 'normalized');
get(h1, 'Position');
set(h1,'Position',[  0.12    0.22    0.18    0.33]);
%colormap setting needs to come after each subplot
shading interp;
colormap jet(500);%colormap need to be set to jet for Blue-yellow-red map

%font properties
FS='Fontsize';
fs1=20;
fs2=20;
FN='Fontname';
fn='Times New Roman';
set(findall(gcf,'type','axes'),FS,fs1,FN,fn);
set(findall(gcf,'type','text'),FS,fs2,FN,fn);
x0=100;
y0=100;
width=700;
height=500;
set(gcf,'units','pixels','position',[x0,y0,width,height]);

Answer 1

[Ajay Kumar]

https://uk.mathworks.com/help/matlab/creating_plots/graph-with-multiple-x-axes-and-y-axes.html

[Zihad Azad]

Thanks. But using this I have run into another problem. Basically, I am using this to plot a curve of zeros:

How do I get rid of the line plot in the middle?

The code:

clc; clear all;
load infinite;
% transpose matrix is not required
A1= log10(fs1);
kx=ky;
h1=figure
p1=pcolor(kx*1e-6,f/1e12,A1);
xlabel('\it{k_x} (\rm{\times10^6 m^{-1}})');ylabel('{\itf} (THz)');
ylim([33 1600]);
set(h1, 'Units', 'normalized');
get(h1, 'Position');
set(h1,'Position',[  0.12    0.22    0.18    0.33]);
%colormap setting needs to come after each subplot
shading interp;
colormap jet(500);%colormap need to be set to jet for Blue-yellow-red map
ax1 = gca; % current axes
ax1_pos = ax1.Position; % position of first axes
ax2 = axes('Position',ax1_pos,'XAxisLocation','top','YAxisLocation','right','Color','none','YTick',[],'TickLength',[.00014 .0014]);
xlabel(ax2,'\rm lambda(\mum)');
l=(2*pi)/ky;
L=length(l);
y=zeros(L);
line(l*1e7,y,'Parent',ax2,'Color','k','linewidth',2);
set(ax2,'XDir','reverse');
% set(gcf,'visible','off');




%font properties
FS='Fontsize';
fs1=20;
fs2=20;
FN='Fontname';
fn='Times New Roman';
set(findall(gcf,'type','axes'),FS,fs1,FN,fn);
set(findall(gcf,'type','text'),FS,fs2,FN,fn);
x0=100;
y0=100;
width=700;
height=500;
set(gcf,'units','pixels','position',[x0,y0,width,height]);

[Ahmed Hassebo]

Remove this line from the second code

% line(l*1e7,y,'Parent',ax2,'Color','k','linewidth',2);