How can I remove negative values from vector (Half-Wave Rectification)

I need help removing the negative values from a vector. I I started with an EMG signal and converted the signal from the time domain to the frequency domain using fft. Next I applied a bandpass filter from 25-400 Hz to get a filtered signal. Now I need to apply a half wave rectification. I would like to use a for loop to remove the ngative values from v_mag_filtered. I'd appreciate the help, I'm a bit rusty on MATLAB

% Time Signal

max_index = 10000;

freq = 960;

t_step = 1/freq;

for i = 1:max_index

t(i) = (i-1)*t_step;

v(i) = EMG(i) * 1E-6;

end

% Power spectrum

for i = 1:max_index

freq_range(i) = (1/t_step)*(i-1)/max_index;

end

v_freq = fft(v,max_index); %complex vector of ECG singal

v_mag = 2*v_freq.*conj(v_freq)/(max_index)^2; %phase information of complex number removed

x = freq_range(1:max_index/2);

y = v_mag(1:max_index/2);

%band pass filter

v_freq_filtered = v_freq;

for i = 1:max_index

if ((freq_range(i)<25))

v_freq_filtered(i) = 0.0;

end

if ((freq_range(i)>400))

v_freq_filtered(i) = 0.0;

end

end

v_mag_filtered = 2*v_freq_filtered.*conj(v_freq_filtered)/(max_index)^2;

Answer 1

[madhan ravi]

 vector = [1, -1];
 vector( vector < 0 ) = 0 % [] to remove

Answer 2

[Star Strider]

Try this:

t = linspace(0, 6*pi, 1E+5);
s = sin(t);

idx = s >= 0;                               % Conditional Logical Index
s_hwr = s.*idx;                             % Signal With Half-Wave Rectification

figure
plot(t, s_hwr)
grid
ylim([-1 1])

This will work regardless of your signal. Since ‘EMG’ is not provided, I use ‘s’ instead here.

[Charlotte Anderson]

Could you explain why you chose those values to input into the linspace function?

[Star Strider]

Sure!

I chose 3 cycles to provide a representative waveform, and elements to produce a smooth plot. All of these (in this example) are arbitrary, so choose whatever values you want (within reason, and within the available memory capacity of your computer) to experiment with.

Answer 3

[m.venkata manohar reddy]

Find the Fourier series of the function obtained by

passing the sinusoidal voltage v(t) = v0 cos(100πt)

through a half wave rectifier given in figure that clips

the negative waves