Single precision in Simulink?

Hi,

how to set the single precision in Simulink? I know how to convert
input or output double values y into single values x:
x=single(y)

But how can i ensure that all operations made i Simulink model are
made with single-precision? Namely, if i have a sinusoidal source, how
can i ensure that values of this source are single precision values?
.