How can filter in Matlab

Please how can I filter a signal in matlab using a filter
impulse response not as a polynomial but just
as an expression h(t)

At the command propt type in:

help remez

Here are some other filters

CREMEZ, FIRLS, FIR1, FIR2, BUTTER, CHEBY1, CHEBY2, ELLIP,
FREQZ, FILTER and GREMEZ

hi,
you may have to evaluate the function h(t) at your sampling intervals and then use it. Thus the length of the filter will vary. This is assuming you are using sampled data.
If you want analog response, you should use symbolic toolbox.(or something like that)
brm

you can try firpm.
using help menu will be very useful...