I am new to using MATLAB and used a plot to generate the graph for a simple sinusoid. The plot is that of a $50$Hz signal, $y=20\sin(100\pi t)$; it was plotted from $-1$ to $1$ sec
the plot which I got was this
I thought that the problem might be with my $x$ axis range, (although still the graph should not be as uneven. This looks more like a mixture of multiple sinusoids than a single, at least the peaks should be at the same height) and decided to lower my range ($-0.1$sec to $0.1$sec) by reducing the axes stretch on the graph, the figure which I got was this
Now, I got really confused and further lowered the axes limits to ($-0.02$sec to $0.02$sec). This I figured should give me some sense of what is happening, the result I get is
Could any one help me with what is going on, I am absolutely clueless...