Re: Displaying a sin wave horizontally instead of vertically.
jt wrote:
Patricia Shanahan wrote:
....
public static void printSin(PrintStream out,
int wavelength, int cols, int amplitude) {
for (int position = amplitude; position >= -amplitude; position--) {
for (int col = 0; col < cols; col++) {
double angle = 2 * Math.PI * col
/ (double) wavelength;
if (Math.sin(angle) * amplitude >= position) {
out.print("*");
} else {
out.print(" ");
}
}
out.println();
}
}
....
That's beautiful. How did you come up with it?
What should rows and columns represent? (This is the key question for XY
chart drawing). For horizontal sine wave, rows have to represent values,
and columns angles.
When should "*" be printed? When the row represents a value that is less
than or equal to the sine of the angle the column represents.
Need a mapping from angles to columns - I find it easier to think in
whole wavelengths than in e.g. radians, so specify the wavelength in
columns.
How wide should the printout be? No reason not to just ask for the width
in columns.
How high, and how to map between values and rows? Toss up between asking
for the number of rows and calculating the amplitude, or what I actually
did, ask for the amplitude and use that to control the number of rows.
That gave me my parameter set-up. col/wavelength is the angle in whole
rotations. Math.sin needs angles in radians, so multiply by 2*pi.
Math.sin returns the sine wave value in units, effectively with
amplitude 1. Multiply the result by the amplitude to get the value in rows.
I don't know if this answers your questions.
Patricia