How to interpolate pressure

I have Pressure data (Attached file)

and I want to interpolate pressure by 1m, from 5m to 700m.

How can I make the code?

I know interp1, but i can't make the code properly

[Jan]

You have asked for a line fitting the data, but removed the question during I've posted an answer:

L    = linspace(5, 700, length(P));
poly = polyfit(L, P, 1);
PP   = polyval(poly, L);
plot(L, P, '.r', L, PP, 'b');

Answer 1

[KSSV]

load('matlab_Pressure.mat')
L = linspace(5,700,length(PP)) ; 

Li = min(L):max(L) ;
PPi = interp1(L,PP,Li) ;

plot(L,PP,'.r',Li,PPi,'b')