Fourier Analysis for Spatial Frequency

Dear All, I have a 2D Array of sensors measuring a signal and resulting in a 26x26 Matrix. I need to analyse only a line of the matrix or in other word, a 1x26 Matrix. The measured values should be compared with calculated values and then a fourier analysis should be performed for both and after that, the values should be compared once again. The code is as following:

c1 = csvread('1mm calc.csv', 0, 1, [0,1,308,1])  %%Load Calculated data
x1_1 = csvread('1mm calc.csv', 0, 0, [0,0,308,0])  %%Load IC position for calculated

m1 = csvread('1.csv', 0, 2, [0,2,26,2])  %%Load Measured Data
x1 = csvread('1.csv', 0, 0, [0,0,26,0])  %%Load IC position

%Calculate Fourier & Spatial frequency
%for 1mm
C1= (abs(fft(c1)))  %%Perofrm Fourier Transformation for Calculated
v1_1 = 1./x1_1  %%Conver Position to Spatial Doamn forcalculated

M1= (abs(fft(m1)))/(1.457481481481482)  %%Perofrm Fourier Transformation for Measured
v1 = 1./x1  %%Conver Position to Spatial Doamn

subplot(2,1,1); plot(x1_1,c1,'m--',x1,m1,'ok','LineWidth',2)
xlabel('Position [mm]');
ylabel('rel. Reading');
hleg1 = legend('1mm','Measured');

 subplot(2,1,2);plot(v1_1,C1,'m--',v1,M1,'ok','LineWidth',2)
xlabel('Spatial Frequency [1/mm]');
ylabel('rel. Absolute Val. (FFT)');
hleg1 = legend('1mm','Measured');

what i am getting is :

but what i need to get is similar to this:

and the question is, what am i doing wrong? other than shifting the negative part of the fourier analysis to the positive part and normalizing the values to 1. i might also need to pickup specific values to make the analysis easier.

So to the sum up the questions again: 1- Where am i going wrong in the Fourier command part? 2-when the code is loading "c1" & "x1_1", they are 309 values. how can i read the values with a sampling step of ten?

Thanks in advance