Do you know the function Floor and friends? Is it this, what you want?
Floor
Plot[Floor[x], {x, 0, 10}, Exclusions -> None]
Too many curly braces. Try this:
f[x] = Piecewise[{{1.5, -6 < x < -5.8}}]; Plot[f[x], {x, -6.5, -5.5}]
Thanks for that, it show now the function, but the plot is still blank.
Please check your code. There is no [ ] following Piecewise.
[ ]
Piecewise
