I am testing the Simulink discrete integrator block as shown in the picture below. The simulation is fixed step with $T_s = 1e-5$ and the cosine wave block setting and the scope display is also shown below.

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For the discrete integrator block, the gain value K is set to be 1 and the integration method was chosen to be "Accumulation: Forward Euler". However, how come the magnitude of the result is so big as shown in the top part of the scope picture? I thought integrating a cosine wave will produce a sine wave with the same magnitude. If the integration method is chosen to be "integrator: Forward Euler", the result becomes very small, as shown below. It just can't produce a sine wave with magnitude of 1. How to get the correct result? enter image description here


1 Answer 1


All of a sudden I realized I made a silly mistake. $$ \int \cos(\omega\cdot t)dt=\frac{1}{\omega}\sin(\omega\cdot t) $$ which means the "integrator: Forward Euler" choice produced the correct result.


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