from math import sin

def ps(length, amplitude, frequency, bias=1.0):
xarray = range(length)
print (xarray)
yarray = []
for i in xarray:
yarray+=[sin(float(xarray[i])*frequency)+bias]
print (yarray)
for i in yarray:
print(int(round(i*amplitude))*"*")

return

#an ASCII sine wave graphic with python.