The fundamental of signal

Hi all

Iam want to learn how calculate the total harmonic distortion of this signal in the code below? Because I dont know the fundamental,Is it single bar or more than one bar?

sampling frequency is 8000 SPS, and N=32 ,8000/(32)= 250 HZ,

 signal=[1.9014e-48 4.8553e-55 1.9014e-48 7.7003e-48 1.7394e-47 3.1122e-47 4.9311e-47 7.0613e-47 9.6319e-47 1.2888e-46 1.3633e-46 2.1088e-46 4.0393e-46 1.3351e-48 3.5183e-44  7.167e-44 1.4889e-42 1.3673e-42 1.4889e-42  7.167e-44 3.5183e-44 1.3351e-48 4.0393e-46 2.1088e-46 1.3633e-46 1.2888e-46 9.6319e-47 7.0613e-47 4.9311e-47 3.1122e-47 1.7394e-47 7.7003e-48];
figure;
hold on 
bar(signal)
hold off
grid;