Question $$Function $($use matlab$)$

$(1).$ Create a function plotSinFunc to recognize the number of input arguments automatically.

$(2).$ If the number of input argument is $1($we can call it like plotSinFunc$($f$1)),$ create a time series

x$=$linspace$(0,$ pi$,$ f$1*20+1),$ and plot the sin$(2$x$).$ You should use squares as markers and a dashed

red line of thickness $2$ for the line. Set the marker face color to be black $($properties are

LineWidth, MarkerFaceColor$)$

$(3).$ If there are $2$ inputs, i$.$e$.$ function usage like plotSinFunc$($f$1,$ f$2),$ create two time series

x$1=$linspace$(0,$ pi$,$ f$1*20+1)$ and x$2=$linspace$(0,$ pi$,$ f$2*15+1),$ and, open a new figure with $2$ axes,

plot sin$(2*$x$1)$ on top and plot sin$($x$2)$ on the bottom.

$(4).$ If the number of input arguments is other, display 'Only one or two inputs are allowed'.

$(5).$ Think about the possibility of a negative number as the input. How to recognize it in your

function, and try to write a robust function.

$(6).$ In a script $.$m file to call the plotSinFunc with the input arguments:

a$)$ Only one arguments: $12$

b$)$ Two arguments: $(12,60)$

c$)$ Two arguments: $(12,-12)$

Hint: the number of input arguments are in the built$-$in variable nargin.