The line for my graph isn't showing. Also, only the 'van der Waals equation' shows up on my legend.

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Corey Smith 2017-9-25

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回答： Niraj Gadakari 2017-9-28

x=(1*0.08206*373.15)./0.06706468 y=-(3.592*1*0.04267)./((0.08206*373.15*0.04267)-3.592) plot(x,y) xlabel('Volume, (L)') ylabel('Pressure, (atm)') axis([0 1 0 400]) legend('van der Waals equation','Ideal Gas equation')

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Answer 1

Niraj Gadakari 2017-9-28

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In the code there is no line. You just have a scalar value x = 456.5844, y = 0.0671.

If one of X or Y is a scalar and the other is either a scalar or a vector, then the plot function plots discrete points. However, to see the points you must specify a marker symbol, for example, plot(X,Y,'o'). Refer to the documentation for plot function.

Also, you are setting the axis limit beyond the data point.

You can see your data point by executing the following code:

 x=(1*0.08206*373.15)./0.06706468; 
 y=-(3.592*1*0.04267)./((0.08206*373.15*0.04267)-3.592); 
 plot(x,y,'o') 
 xlabel('Volume, (L)') 
 ylabel('Pressure, (atm)')