Two x-axis for the same y-axis

Hello dear altruist,

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

I tried from my end and this is the result. The x-axis on top is just normalized scale from 0 to 1 in reverse. Basically, the x-axis values at the top needs to be 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
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);
hold(ax2,'on');
% plot(ax2,l*1e7,y);
% line(l*1e7,y,'Parent',ax2,'Color','k');
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]);

Answer 1

[Jakob B. Nielsen]

You're on the right track with some of the stuff you have tabbed out. All you need is to set the x and y limits for your ax2 axes.

set(ax2,'XDir','reverse');
ylim(ax2,[33 1600]);             %set the y and x limits on ax2
xlim(ax2,[0 100])

From here, you can just change the ax2 x axis limits to be whatever you want them to be, and use the regular commands for the ticks etc.

[Zihad Azad]

Thanks, I got it now