spirplot2.html

Experiment #2

In this experiment we used a turitella shell to plot a logarithmic spiral.

To do this we had to:

1. Attach a thin string to the base of the shell with a piece of tape;

2. Wrap the string around the shell until reaching the apex of the shell and then tape this end of the string to a pencil;

3. Holding the tip of the shell steadily in place on a piece of paper, unravel the string while drawing on the paper with the pencil (similar to using a compas);

4. Let your starting point be the origin and draw an x and y-axis;

5. Measure every 30 degrees from the x-axis from 0 to 360;

6. Measure the distance from the origin to the point on the spiral at every 30 degree interval;

7. With these measurements, we are now able to plot the results using Maple.

> restart;with(plots):with(stats):plotsetup(inline):readlib(readdata):readlib(readline):

> readline("a:/spirdata2.txt");Tu:=readdata(`a:spirdata2.txt`,2);

The "Tu" stands for turitella the name of the shell used for this data.

> plot(Tu,coords=polar);

> Avalues:=evalf([seq(Tu[i,2],i=1..27)]*Pi/180);

> Rvalues:=[seq(Tu[i,1],i=1..27)];

> Lvalues:=[seq(ln(Tu[i,1]),i=1..27)];

Avalues represents the angles in radians, Rvalues the radius in cm and Lvalues the ln of the Rvalues.

(SP, for spiral.)

> SP:=[seq([Lvalues[n],Avalues[n]],n=1..27)];

> plot(SP,style=point,symbol=circle);

From here I do not know what to do. It is more complicated to fit this shell since it is three dimensial. We therefore have to take into account the angle of inclination, the distance from the base, etc.

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