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From: kaleigh on 1 Aug 2010 23:43
I am trying to plot something in matlab and cannot get anything but the axis showing up..

I have a 6x6 matrix with sind(i) and cosd(i) in it, where i is an angle I need to vary from 0 to 30 degrees. My code I am using is

for i = 0:1:30
A= [-1 0 0 0 0 1; 0 -1 0 1 0 0; -1 0 1 0 1 0; (.3*(cosd(i))) 0 0 0 0 0; ((-.3*(sind(i))+.4)) 0 0 0 .8 0; (.3*(cosd(i))) 0 0 -.8 0 0];
C = [0; 0; 981; 98.1; 490.5; 0];
D=inv(A);
F=D*C;
plot(F(6,:),i);
end

Where F= [P, Ryb, Rzb, Rya, Rza, Rxa] and I need the plot of Rxa verse i (0-30 degrees).

I am not very familiar with matlab so this maybe completely wrong but please help.
From: Roger Stafford on 2 Aug 2010 00:54
"kaleigh " <itsmeklee14(a)yahoo.com> wrote in message <i35esb$7q4$1(a)fred.mathworks.com>...
> I am trying to plot something in matlab and cannot get anything but the axis showing up..
>
> I have a 6x6 matrix with sind(i) and cosd(i) in it, where i is an angle I need to vary from 0 to 30 degrees. My code I am using is
>
> for i = 0:1:30
> A= [-1 0 0 0 0 1; 0 -1 0 1 0 0; -1 0 1 0 1 0; (.3*(cosd(i))) 0 0 0 0 0; ((-.3*(sind(i))+.4)) 0 0 0 .8 0; (.3*(cosd(i))) 0 0 -.8 0 0];
> C = [0; 0; 981; 98.1; 490.5; 0];
> D=inv(A);
> F=D*C;
> plot(F(6,:),i);
> end
>
> Where F= [P, Ryb, Rzb, Rya, Rza, Rxa] and I need the plot of Rxa verse i (0-30 degrees).
>
> I am not very familiar with matlab so this maybe completely wrong but please help.
- - - - - - - - - - - -
You need to do a "hold on" so that the successive points plotted do not erase previous points. If you look carefully at your plot you should see the last surviving point there as a single tiny point for i = 30.

Another way is to store successive values of Rxa in an array and do the plot on this array versus the array 0:30 .

Roger Stafford
From: William on 2 Aug 2010 01:01
Is the vector 'A' significant to somthing? Was it just a matrix you need to recreate?
From: Ross W on 2 Aug 2010 02:56
"Roger Stafford" <ellieandrogerxyzzy(a)mindspring.com.invalid> wrote in message <i35j1b$pal$1(a)fred.mathworks.com>...
> "kaleigh " <itsmeklee14(a)yahoo.com> wrote in message <i35esb$7q4$1(a)fred.mathworks.com>...
> > I am trying to plot something in matlab and cannot get anything but the axis showing up..
> >
> > I have a 6x6 matrix with sind(i) and cosd(i) in it, where i is an angle I need to vary from 0 to 30 degrees. My code I am using is
> >
> > for i = 0:1:30
> > A= [-1 0 0 0 0 1; 0 -1 0 1 0 0; -1 0 1 0 1 0; (.3*(cosd(i))) 0 0 0 0 0; ((-.3*(sind(i))+.4)) 0 0 0 .8 0; (.3*(cosd(i))) 0 0 -.8 0 0];
> > C = [0; 0; 981; 98.1; 490.5; 0];
> > D=inv(A);
> > F=D*C;
> > plot(F(6,:),i);
> > end
> >
> > Where F= [P, Ryb, Rzb, Rya, Rza, Rxa] and I need the plot of Rxa verse i (0-30 degrees).
> >
> > I am not very familiar with matlab so this maybe completely wrong but please help.
> - - - - - - - - - - - -
> You need to do a "hold on" so that the successive points plotted do not erase previous points. If you look carefully at your plot you should see the last surviving point there as a single tiny point for i = 30.
>
> Another way is to store successive values of Rxa in an array and do the plot on this array versus the array 0:30 .
>
> Roger Stafford

In addition to Roger's suggestion, you might also consider replacing

plot(F(6,:),i);

by

plot(F(6,:),i, 'o');

or some other marker. Read the help for plot to learn more...

Cheers,
Ross
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