How do you use the "interp1" command?

I am working on this code and for some reason i cant sure out why im getting a error. plss lmk if you

N = 128
delta_x = 2/N

x = [0:2/N:1, 1:-2/N:0]
y_int_top = interp1 (x_c, y_top, x(1, 1:65) )
y_int_bot = interp1 (x_c, y_bot, x(1, 66:130))
y_t = [y_int_top, y_int_bot]

% for i=1:N
%     x(i) = x(i-1)+delta_x
% 
%     theta_top(i) = atan2d((y_top(i+1)-y_top(i)),((x(i+1)-x(i))));
%     theta_bot(i) = atan2d((y_bot(i+1)-y_bot(i)),((x(i+1)-x(i))));
% end

[KSSV]

What error you are getting? You should psecify the error and it's line number.

[Diego Portillo]

Error using interp1>reshapeAndSortXandV (line 435)

X must be a vector of type double or single.

Error in interp1 (line 128)

[X,V,orig_size_v] = reshapeAndSortXandV(X,V);

Error in compassignment (line 5)

y_int_top = interp1 (x_c, y_top, x(1, 1:65) )

[KSSV]

What is size of x_c, y_top? Theys hould be vectors.

[Diego Portillo]

they are a tables i think. I am not very proficient with Matlab so i am not sure if they already are in vector form

Answer 1

[KSSV]

Try:

y_int_top = interp1 (x_c.(1), y_top.(1), x(1, 1:65) ) ;
y_int_bot = interp1 (x_c.(1), y_bot.(1), x(1, 66:130)) ;

[Diego Portillo]

it now gives me a different error, idk if this one is related to the data?

```Error using matlab.internal.math.interp1

Sample points must be unique and sorted in ascending order.

Error in interp1 (line 188)

VqLite = matlab.internal.math.interp1(X,V,method,method,Xqcol);

Error in compassignment (line 5)

y_int_top = interp1 (x_c.(1), y_top.(1), x(1, 1:64) ) ;```

[KSSV]

Try spline instead of interp1.

N = 128
delta_x = 2/N
x = [0:2/N:1, 1:-2/N:0]
y_int_top = spline(x_c, y_top, x(1, 1:65) )
y_int_bot = spline (x_c, y_bot, x(1, 66:130))
y_t = [y_int_top, y_int_bot]