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Sin Frequencies Precal

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import numpy as np
import matplotlib.pyplot as plt
from IPython.display import Audio

SAMPLE_RATE = 44100

def make_note(frequency, duration, volume=1.0):
    t = np.linspace(0, duration, int(SAMPLE_RATE * duration), endpoint=False)
    wave = volume * np.sin(2 * np.pi * frequency * t)

    fade_len = int(0.025 * SAMPLE_RATE)  # 20ms fade
    wave[:fade_len]  *= np.linspace(0, 1, fade_len)   # fade in
    wave[-fade_len:] *= np.linspace(1, 0, fade_len)   # fade out

    return wave

notes = {

    'C4': 261.63,
    'D4': 293.66,
    'E4': 329.63,
    'F4': 349.23,
    'G4': 392.00,
    'A4': 440.00,
    'B4': 493.88,
    'C5': 523.25,
    'D5': 587.33,
    'REST': 0
}


melody = [
    ('E4', 0.8),
    ('G4', 0.4),
    ('D5', 1.2),
    ('C5', 0.8),
    ('G4', 0.4),
    ('F4', 1.2),
    ('E4', 0.8),
    ('E4', 0.4),
    ('REST', 0.2),
    ('E4', 0.4),
    ('F4', 0.4),
    ('G4', 1.2),
    ('F4', 1.2),
    ('E4', 0.4),
    ('E4', 0.4),
    ('F4', 0.8),
    ('G4', 1.2),
    ('C5', 0.8),
    ('C5', 0.4),
    ('G4', 0.8),
    ('E4', 0.4),
    ('D4', 0.4),
    ('E4', 0.4),
    ('F4', 1.2),
    ('G4', 0.4),
]

song = np.array([])  # start with an empty array

for note_name, duration in melody:
    freq = notes[note_name]
    if freq == 0:
        # REST: just add silence
        song = np.concatenate([song, np.zeros(int(SAMPLE_RATE * duration))])
    else:
        song = np.concatenate([song, make_note(freq, duration)])


song = song / np.max(np.abs(song))
Audio(song, rate=SAMPLE_RATE)