PRO idl_hw1_acp
; acp is for Aaron Paget
; The purpose of this homework is to make a cosine wave plot with
; wavelength of 2*PI for two cycles of phases 0,15,30,45,60,75,90 (degrees)
; In order to do this, I will first build an x array such that I have a 
; value at every point (or degree) so it looks really good
; Here we build the x array indexed from 0 to 720 
x = FINDGEN(721) ; FP indexed array
x = x * 1.  ; sets range to 0:720, step 1, as reals
;
; Now that we have the array built, we need to construct the cosine function
; which depends on x and the phase shift. To shift the phase to the left, 
; you need to add the shift from the arguement in the cosine.
;
; For the initial case, the phaseshift will be 0 incrimenting by 15 up to 90
; in degrees. Changing the arguement into radians is accomplished with the 
; !DTOR.
;
phaseshift=0.
y0 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
; now we create the rest of the lines
phaseshift=15.
y15 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
phaseshift=30.
y30 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
phaseshift=45.
y45 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
phaseshift=60.
y60 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
phaseshift=75.
y75 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
phaseshift=90.
y90 = COS(x * !DTOR + phaseshift * !DTOR ) ; cosine of x in degrees
;
; The plots must be made. First the window is created appropiately 
; and approximately the size of the sample, at least in proportional 
; dimensions. Labeling the x and y coordinates gives some perspective
; with tick marks matching.
; The initial plot is made with overlays for each additional phase.
;
WINDOW, XSIZE=700,YSIZE=800
PLOT, x, y0,$
	XRANGE=[0,720], XSTYLE=1, YRANGE=[-1.2,1.2], YSTYLE=1, $
	XTITLE='DEGREES', YTITLE='COSINE', $
	XTICKINTERVAL=90, XMINOR=2, XCHARSIZE=1.5, YCHARSIZE=1.5, THICK=2, $
	COLOR='00'X, BACKGROUND='ffffff'X,$;
	POSITION=[.1,.2,.9,.9]
OPLOT, x, y15, THICK=2, COLOR='00'X, LINESTYLE=1 ; 
OPLOT, x, y30, THICK=2, COLOR='00'X, LINESTYLE=2 ; 
OPLOT, x, y45, THICK=2, COLOR='00'X, LINESTYLE=3 ; 
OPLOT, x, y60, THICK=2, COLOR='00'X, LINESTYLE=4 ; 
OPLOT, x, y75, THICK=2, COLOR='00'X, LINESTYLE=5 ; 
OPLOT, x, y90, THICK=2, COLOR='00'X, LINESTYLE=6 ; 
;
; The legend is generated here. The legend has all of the values of the phases
; spaced along the bottom and placed appropiate to match the origional.
;
XYOUTS, .14,.1,'0',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .23,.1,'15',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .34,.1,'30',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .45,.1,'45',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .57,.1,'60',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .67,.1,'75',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .78,.1,'90',/NORMAL, SIZE=1.5, COLOR=0
XYOUTS, .5,.91,'COSINE WAVE WITH PHASES',/NORMAL, ALIGN=.5, SIZE=1.9, COLOR=0
;
; In order to make the lines appear on the bottom as a legend, a new plot
; is generated. Two arrays are built for initial sampling and positioning
; as well as avoiding the use of a /NODATA command.
; A plot is made in a position close to the bottom of the page.
;
x1=FINDGEN(721)-20
y1=FINDGEN(721)*0.

PLOT, x1(20:41),y1,$
	XRANGE=[-20,721], XSTYLE=5, YRANGE=[-1.5,1.5], YSTYLE=5, $
	THICK=2,/NOERASE,XTHICK=0,YTHICK=1, $
	COLOR=0, BACKGROUND='ffffff'X ,$;
	POSITION=[.05,.06,.9,.15], LINESTYLE=7
;
; The lines are generated for the legend on this new plot
;
OPLOT, [0,40], [0.0,0.0], COLOR=0, THICK=2, LINESTYLE=0
OPLOT, [90,130], [0,0], COLOR=0, THICK=2, LINESTYLE=1
OPLOT, [180,220], [0,0], COLOR=0, THICK=2, LINESTYLE=2
OPLOT, [280,320], [0,0], COLOR=0, THICK=2, LINESTYLE=3
OPLOT, [380,420], [0,0], COLOR=0, THICK=2, LINESTYLE=4
OPLOT, [475,515], [0,0], COLOR=0, THICK=2, LINESTYLE=5
OPLOT, [565,605], [0,0], COLOR=0, THICK=2, LINESTYLE=6
;
; Por fin. Ya cumplimos el proposito de la tarea.
; (Finally. Now we are done with the purpose of the homework.)
; You never indicated which language to comment in.
; maybe german next time.
;
END