Does changing the axes turn tick marks off?

I've tried to adjust my tick marks but they don't even exist anymore. Plenty of help on how to get rid of tick marks but absolutely nothing out there on how to turn them on. My code is listed below. The end of it is really all that's relevant.

• syms x1 x2;
• y1 = x1^2;
• slope_y1 = diff(x1^2);
• slope_y2 = -1/subs(slope_y1,2);
• %y = mx+b
• %y-mx = b
• b = 4-slope_y2*2;
• y2 = slope_y2*x2+b;
• x_intercept_y2 = solve(y2,0);
• area_y1 = int(y1,0,2);
• area_y2 = int(y2,2,x_intercept_y2);
• area = area_y1+area_y2
• figure
• hold on
• x1 = 0:.01:2;
• y1 = eval(vectorize(y1));
• plot(x1,y1,'LineWidth',2,'color','b')
• x2 = 2:.01:18;
• y2 = eval(vectorize(y2));
• plot(x2,y2,'LineWidth',2,'color','r')
• x3 = (0:.01:18);
• plot(x3,0,'LineWidth',2,'color','m')
• plot([-2 20],0, 'k')
• axis([-2 20 -1 5])
• plot([-2 0],[0 0],'k')
• plot([18 20],[0 0],'k')
• plot([0 0],[-2 5],'k')
• set(gca,'Xtick',[5 10 15])

Could someone please tell me where I went wrong?

Answer 1

[Giorgos Papakonstantinou]

If you want to remove the ticks from both x axis and y axis , do this:

set(gca,'Xtick',[], 'Ytick', [])

[Haden Mattke]

I want to ADD tick marks

[Giorgos Papakonstantinou]

Sorry I understood the opposite. When I execute your code I see tick marks at exactly where you want them i.e. 5, 10, 15

[Haden Mattke]

Thanks for taking a look. I was intending to change gridlines, not tick marks. I just needed to use {grid on}

Answer 2

[Star Strider]

See Axis Properties, specifically Tick Values and Labels. I don’t see where you might have turned your tick marks off, so I would comment-out various plotting lines until I found the guilty one. One possibility to get them back is to add 'XTickLabel' to your set call:

set(gca,'Xtick',[5 10 15], 'XTickLabel',[5 10 15])