The paper presents numerical solving methods using MATLAB programming language of the governing equation of the liquid oscillations in a U-tube liquid manometer with equal diameter columns. Assuming some numerical values for geometrical and functional parameters of this pressure measurement system, the dynamic behavior of the oscillating system will be analyzed using four MATLAB based computational methods: the method of the default MATLAB procedures, the Simulink method, the Simscape method and the method of the Control System Toolbox procedures. According to all these methods, in almost all the cases analyzed, the dynamic behavior of the U-tube liquid manometer with equal diameter columns corresponds to an under-damped dynamic system. The influence of some important constructive and functional parameters (the columns diameter, the manometer liquid, the capillarity action and the connection tube between the reservoir and the manometer) has been investigated. Improving the dynamic response (decreasing the overshoot and the settling time, increasing the phase and delay margins) can be achieved by increasing the connection tube length, by decreasing the columns diameter and by using a high density liquid manometer.