MatLab returning different trigonometric answers than calculator?

Question

I'm having some difficulty trying to comprehend the answers that Matlab and my calculator are returning from sinusoidal functions.

Firstly, I figured that pi/2 and 90 deg are analogous, but when I pass them into a cosine function I get these two outputs:

• Calculator: cos(90) = 0
• Calculator: cos(pi/2) = 0.9996242169
• Matlab: cos(90) = -0.4481
• Matlab: cos(pi/2) = 6.1232e-17

I have been referencing the unit circle and things don't seem to stack up. I am fairly new to maths, so maybe I may be doing something wrong. I've been practising with the sine function and this is a lot closer to my calculator results:

• Matlab: sin(90) = 0.8940
• Matlab: sin(pi/2) = 1

Answer 1

If you want to provide angle in degrees then use cosd and sind and if angle is in radians then use cos and sin.

cos(0) and cosd(0) are producing 1 on my computer. However cos(pi/2) is producing 6.1232e-17 and cosd(90) is producing 0.

you can check matlab specification which number is close to 0.