xsegs draw unconnected segments

## Syntax

                xsegs(xv, yv, [style])
                xsegs(xv, yv, zv,[style])

## Arguments

xv, yv, zv

  matrices of the same size. If `zv` is not specified, a zero vector is used.

style

  vector or scalar. If `style` is a positive scalar, it gives the color to use for all segments. If `style` is a negative scalar, then current color is used. If `style` is a vector, then `style(i)` gives the color to use for segment `i`.

## Description

`xsegs` draws a set of unconnected segments given by `xv`, `yv` and `zv`. If `xv`, `yv` and `zv` are matrices they are considered as vectors by concatenating their columns. The coordinates of the two points defining a segment are given by two consecutive values of `xv`, `yv` and `zv`:

`(xv(i),yv(i),zv(i))-->(xv(i+1),yv(i+1),zv(i+1))`.

For instance, using matrices of size `(2,n)`, the segments can be defined by:

    xv=[xi_1 xi_2 ...; xf_1 xf_2...]
    yv=[yi_1 yi_2 ...; yf_1 yf_2...]
    zv=[zi_1 zi_2 ...; zf_1 zf_2...]

and the segments are `(xi_k,yi_k,zi_k)-->(xf_k,yf_k,zf_k)`.

## Examples

    // 2D example
    x=2*%pi*(0:9)/10;
    xv=[sin(x);9*sin(x)];
    yv=[cos(x);9*cos(x)];
    plot2d([-10,10],[-10,10],[-1,-1],"022")
    xsegs(xv,yv,1:10)

x=2*%pi*(0:9)/10; xv=[sin(x);9*sin(x)]; yv=[cos(x);9*cos(x)]; plot2d([-10,10],[-10,10],[-1,-1],"022") xsegs(xv,yv,1:10)

    // 2D example
    plot2d([-10,10],[-10,10],[-1,-1],"022")
    xsegs([9, -9],[9 , -9]) // Draw the line from X(9,9) to Y(-9, -9)
    xsegs([5, -2],[4 , -1]) // Draw the line from X(5,4) to Y(-2, -1)

plot2d([-10,10],[-10,10],[-1,-1],"022") xsegs([9, -9],[9 , -9]) // Draw the line from X(9,9) to Y(-9, -9) xsegs([5, -2],[4 , -1]) // Draw the line from X(5,4) to Y(-2, -1)

    // 3D example
    clf();
    a=gca();
    a.view="3d";
    f=gcf();
    f.color_map=rainbow(120);
    alpha=2*%pi*(0:119)/40;
    xv=[sin(alpha)/2;sin(alpha)/3];
    yv=[cos(alpha)/2;cos(alpha)/3];
    zv=[alpha/8;alpha/8];
    xsegs(xv,yv,zv,1:120);
    // Now adjust the data_bounds
    a.data_bounds = [min(xv) min(yv) min(zv); ...
                     max(xv) max(yv) max(zv)];
    // We can add an arrow to each segs
    e = gce();
    e.arrow_size = 0.4;

a=gca(); a.view="3d"; f=gcf(); f.color_map=rainbow(120); alpha=2*%pi*(0:119)/40; xv=[sin(alpha)/2;sin(alpha)/3]; yv=[cos(alpha)/2;cos(alpha)/3]; zv=[alpha/8;alpha/8]; xsegs(xv,yv,zv,1:120); a.data_bounds = [min(xv) min(yv) min(zv); ... max(xv) max(yv) max(zv)]; e = gce(); e.arrow_size = 0.4;