help in matlab please. I have the 1st order forward difference. need help with the rest

Using the RVPres waveform from HW07, in HW07.mat (recalling that it was collected with a time step of 4ms): Using a 1st order forward difference, find the first and second time derivatives of RVPres. Using a 6th order central difference, find the first time derivative of RVPres, which in the code below I'll call "DP6th"; then o Apply smoothing to the derivative using the following commands: Wp = 0.004*2*20; % dt * 2 * cutoff frequency [b,a] = butter(20, Wp); % Butterworth Filter DP smooth - filtfilt(b,a, DP6th); % perform the filter Again find the 2nd derivative of pressure using a 6th order central difference of the smoothed 6th order dP/dt. (DPsmooth in the code above) Use the trapezoidal rule to integrate the smoothed 6th order dP/dt (DPsmooth) to obtain a new "smoothed" pressure waveform. Plot on separate figures, from time=0 to time=1.0 sec: The pressure and the "smoothed" pressure The original (1st order forward) d/dt, the 6th order dP/dt, and the smoothed 6th order dp/dt The original (1st order forward) d2P/dt>, and the 6th order central difference of the smoothed 6th order dP/dt. Using the RVPres waveform from HW07, in HW07.mat (recalling that it was collected with a time step of 4ms): Using a 1st order forward difference, find the first and second time derivatives of RVPres. Using a 6th order central difference, find the first time derivative of RVPres, which in the code below I'll call "DP6th"; then o Apply smoothing to the derivative using the following commands: Wp = 0.004*2*20; % dt * 2 * cutoff frequency [b,a] = butter(20, Wp); % Butterworth Filter DP smooth - filtfilt(b,a, DP6th); % perform the filter Again find the 2nd derivative of pressure using a 6th order central difference of the smoothed 6th order dP/dt. (DPsmooth in the code above) Use the trapezoidal rule to integrate the smoothed 6th order dP/dt (DPsmooth) to obtain a new "smoothed" pressure waveform. Plot on separate figures, from time=0 to time=1.0 sec: The pressure and the "smoothed" pressure The original (1st order forward) d/dt, the 6th order dP/dt, and the smoothed 6th order dp/dt The original (1st order forward) d2P/dt>, and the 6th order central difference of the smoothed 6th order dP/dt