Complex number and degrees

Hi,

result of code

x=3*cos(pi)+3*sin(pi)*i

is -3.0000 0.0000i.

But result of this code

x=3*cosd(180)+3*sind(180)*i

is -3.

Why result of second code is not in form -3.0000 0.0000i.???

How can I do this without transformation from deg to rad???

Thank you

x=3*cos(pi)+3*sin(pi)*

[Matt Kindig]

In short, numerical precision. In the first case, MATLAB represents sin(pi) as 3.6739e-16 (on my x64 machine), while in the second case, sind(180) is identically zero. Both are equivalent.

Answer 1

[Azzi Abdelmalek]

Because of precision problem with pi

sin(pi)=1.2246e-16

and

sind(180)=0

Answer 2

[Youssef Khmou]

hi Jhon,

i can not say why using cosd and sind gives only double not complex, but you can use exponential representation which is commonly used in Elec,Eng :

R= Magnitude * exp(j* Angle ) in radian

 r=3*exp(j*pi)

[Youssef Khmou]

ok then its about precision