Complex Numbers where thy are not supposed to be
6 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Adrian Alexander
am 8 Apr. 2021
Kommentiert: Adrian Alexander
am 12 Apr. 2021
Hi I had this Problem a number of times now and I dont get it.
I get Complex Numbers as results, however i need normal Numbers.
I simplified the code. its a sinus going through an dsp algorithm for an audio plugin.
The negative Halfwave of the Sinus causes the output to become Complex.
1-1^2.5 = 0
but when i run the code i get
1-1^2.5= 1.0000 + 1.0000i
How can i tell matlab that no Complex Calculus is needed ?
x=[0 ; 1 ; -1 ; 0]
N = length(x);
y=zeros(N,1)
for n=1:N
y(n,1) = (1+x(n,1)^2.5)
end
%thank u in advance ;)
0 Kommentare
Akzeptierte Antwort
Jan
am 8 Apr. 2021
Bearbeitet: Jan
am 8 Apr. 2021
1 - 1^2.5 == 0 % Let's ignore the rounding errors...
This is correct. But you calculate something else:
x = -1;
1 + x^2.5
This is:
1 + (-1)^2.5
which is 1 + 1i. The parentheses matter. Or if you store the -1 in a variable, the code is equivalent to:
1 + (x)^2.5
"How can i tell matlab that no Complex Calculus is needed?"
You can't. The result of 1+(x)^2.5 with a negative x is complex and you cannot convert this to 0 - except with catching these values explicitly:
y = zeros(N, 1);
for n = 1:N
if x(n) >= 0
y(n) = 1 + x(n)^2.5;
end
end
2 Kommentare
Steven Lord
am 8 Apr. 2021
Another possibility is that the poster intended to raise the expression to the 2.5 power not just the variable.
x = -1;
y1 = (1+x^2.5)
y2 = (1+x)^2.5
Of course in this case there's no need for a loop with the example as written if you use the elementwise power operator .^ instead of the matrix power operator ^ as below.
x = [0 1; -1 0];
y3 = (1+x).^2.5
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Fourier Analysis and Filtering finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!