Integral formula

please hows we write in FF++, the formula:
\int_{t-\tau-h}^{t-\tau+h} I(x,s) ds
where h is an integer avec I(x,s) is function solution of an other problem


The simple way to create a meshL Thl of size -h,h
the you can also define a other meshL Th1 of size ???

now you have a function of xx

 func real ffff(real xx){return int1d(ThI)( I(xx,t-t-tau+x) );}