simple 2d plot

[spectre]

Hi,

I'm using freemat under linux and it works perfectly.I'm a newbie,so sorry for my banal? question

I want to plot something like this,is it possible ? Let me to explain:

I have an x,y point on my 2d space, For example x=10, y=10;

using the following: 

x' = x*cos(angle) - Y*sin(angle)

x' = x*sin(angle) + Y*cos(angle)

I can find the x' and y' coordinates.

All I want to do with Freemat is to plot something like the fig1

Is it possible? (for sure) Can you help me ?

best regards

Spectre

[Timothy Cyders]

I'm not perfectly sure what you're asking, but perhaps this will help. At the console, you can make a vector of x values using the colon notation:

x = 0:0.1:1;

This makes the variable x a vector starting at zero, increasing by 0.1 to a final value of 1. You can then assign y values like so:

y = x*sin(pi/12);

Then, simply plot the two vectors:

plot(x,y);

TJ

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[John Yoepp]

Specter,

I think you want to draw all of figure 1, 

including the blue rotated vector and the green arc.

Yes?

Do you also want the point coordinate annotations

(X,Y) and (X',Y')?

Your second formula should be y', not x'.

John Yoepp, PhD

Math, Algorithms, MATLAB

Consulting and Training

[Jonathan Weaver]

Spectre,

 

This will plot something like figure 1 without the annotation.

 

%Define First line, each column is a point, first row is x, second row is y

len = 1;

line1 = [0 len; 0 0];

%Define angle and rotation matrix to calculate x and y together

angle = pi/2/4;

rotMatrix = [cos(angle) -sin(angle); sin(angle) cos(angle)];

%Rotate it

line2 = rotMatrix*line1;

%Rotate it

line3 = rotMatrix*line2;

%Plot the lines, splitting each row into x and y

hold on;

plot(line1(1,:),line1(2,:));

plot(line2(1,:),line2(2,:));

plot(line3(1,:),line3(2,:));

%Define and plot the arc

a = 0:angle/100:angle*2;

plot(len*cos(a), len*sin(a));

%Set the limits on the X and Y for looks

xlim([-0.5*len,1.5*len]);

ylim([-.5*len,1.5*len]);

 

Is that what you're looking for?

 

-Jonathan