PolynomialMod::polym
This input generates an error because 7.5 is not an integer:
PolynomialMod[11 + 37 x, 7.5]This shows a valid use of PolynomialMod:
PolynomialMod[11 + 37x, 7]You can use Mod to reduce coefficients modulo a noninteger modulus:
Mod[CoefficientList[11 + 37x, x], 7.5]