combine t axis with vector?

Hello,

I have a time reference vector t= 723 x 1, and I have a data vector d = 723 x 1.

I want to use harmonics to remove the inter-annual and annual variations but it doesn't seem to work correctly, I guess it must be because my vector does not contain one dimension time. Does anyone know how to combine so that I have a d vector with a correct time reference, rather than simply the index number?

my code:

[amp,phi] = harmonic(t,msld,36.525,0,0);
x = harmonic(t,amp,phi,36.525,0);

I chose 36.525 as one year because my data is split into 10 day cycles..

thanks! Michael