How to see graphs when you run your code?

I dont know if it doesn’t run and show me graphs because there is an error in the code or because I dont press the right keys. Can someone tell me how we go about executing the program to see graphs?

[dpb]

Which "program" are you speaking of, specifically?

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Walter Roberson]

Are the axes showing up but there appears to be no content in them? If that is happening and you are using plot(), then you have probably called plot on only one point when you thought you were creating a line plot. By default plot() uses no Marker so plotting of a single point does not show up at all. You can check if this is the case by adding a marker to the call, such as

plot(x, y, 'Marker', '*')

then if a single dot shows up you know that something was plotted but it was only one point.

It is common for beginners to use a loop that looks something like

   for K = 1 : 10
     x = K * 5;       %x is a single value
     y = x.^2 - 3;    %y is a single value that is some function of x
     plot(x, y);
   end

or they might add a "hold on" after the plot(). This has the difficulty that I noted above: only one point at a time is being plotted and no marker has been given so by default plot does not draw anything.

When plot() is used in a loop to draw one point at a time, it does not instruct the graphics system to join the points. Points are only automatically joined when they are all plotted together.

The way to resolve this is to record the x and y values and do the plot afterwards, such as

for K  1 : 10
  x(K) = K * 5;     %save this particular x value
  y(K) = x(K).^2 - 3;   %use this particular x value, compute this y, and save it
end
plot(x, y)

then x and y are vectors of values, and plot() automatically joins points when vectors of values are given.