png(file="img%05d.png", width=300, height=300, pointsize = 16) plot.bk <- function(s){ 	d1 <<- 1 	d2 <<- 1.5 	My <<- sqrt(d2^2 - d1) 	pause <<- 1L:30L 	angL <<- 30 	ang <<- seq(0,2*pi, length=angL) 	x1 <<- cos(ang)*d2 - d1 	x2 <<- cos(ang+pi)*d2 + d1 	y <<- sin(ang)*d2 	arc <<- seq(0, 2*pi, length=angL*10) 	xarc1 <<- cos(arc)*d2 - d1 	xarc2 <<- cos(arc+pi)*d2 + d1 	yarc <<- sin(arc)*d2  	par(mar=c(0,0,0,0)) 	plot(NULL, xlim=c(-2.1,2.1), ylim=c(-2.1,2.1), type="n", xaxt="n", yaxt="n", asp=1, frame.plot=F) 	lines(c(-1*d1,d1), c(0,0), lwd=2) 	points(c(-d1,d1), c(0,0), pch=20) 	text(-1,0.3,"A") 	text( 1,0.3,"B") 	if(s == 1) {return()}  	lines(c(-1*d2/2,d2/2), c(2,2), lwd=1, col=2) 	if(s == 2) {return()}  	# lines(c(-1,x1[length(x1)]), c(0,y[length(y)]), lwd=1, col=2) 	lines(xarc1[1:length(xarc1)], yarc[1:length(yarc)], col=2) 	if(s == 3) {return()}  	# lines(c( 1,x2[length(x2)]), c(0,y[length(y)]), lwd=1, col=2) 	lines(xarc2[1:length(xarc1)], yarc[1:length(yarc)], col=2) 	if(s == 4) {return()}  	points(c(0,0), c(My,-1*My), pch=20, col=2) 	if(s == 5) {return()}  }  for(i in pause){plot.bk(1)} for(i in pause){plot.bk(2)} lp.x <- seq(-1*d2/2,-1*d1,length=length(pause)) lp.y <- seq(2,0,length=length(pause)) for(i in pause){ 	plot.bk(2) 	lines(c(lp.x[i], lp.x[i]+d2), c(lp.y[i], lp.y[i]), col=2) }  # 左紅一圓 for(i in 1:angL){ 	plot.bk(2) 	lines(c(-1*d1,x1[i]), c(0,y[i]), lwd=1, col=2) 	lines(xarc1[1:(i-1)*10], yarc[1:(i-1)*10], col=2) }  lp.x <- seq(-1*d2/2,d1-d2,length=length(pause)) lp.y <- seq(2,0,length=length(pause)) for(i in pause){ 	plot.bk(3) 	lines(c(lp.x[i], lp.x[i]+d2), c(lp.y[i], lp.y[i]), col=2) }  for(i in 1:angL){ 	plot.bk(3) 	lines(c( d1,x2[i]), c(0,y[i]), lwd=1, col=2) 	lines(xarc2[1:(i-1)*10], yarc[1:(i-1)*10], col=2) }  for(j in pause){plot.bk(4)} for(j in pause){plot.bk(5)} for(j in pause){ 	plot.bk(1) 	points(c(0,0), c(My,-1*My), pch=20, col=2) } Myy <- seq(2, -2, length=length(pause)) for(j in pause){ 	plot.bk(1) 	points(c(0,0), c(My,-1*My), pch=20, col=2) 	lines(c(0,0), c(Myy[1], Myy[j]), col=2) }  for(j in pause){ 	plot.bk(1) 	points(c(0,0), c(My,-1*My), pch=20, col=2) 	lines(c(0,0), c(Myy[1], Myy[length(Myy)]), col=2) }  for(j in pause){ 	plot.bk(1) 	points(c(0,0), c(My,-1*My), pch=20, col=2) 	lines(c(0,0), c(Myy[1], Myy[length(Myy)]), col=2) 	points(0,0,pch=20, col=1) }  for(j in rep(pause, 2)){ 	plot.bk(1) 	lines(c(0,0), c(Myy[1], Myy[length(Myy)]), col=2) 	text(0.3,0.3, "M", col=1) 	points(0,0,pch=20, col=1) 	lines(c(-0.45,-0.45), c(0.1,-0.1)) 	lines(c(-0.55,-0.55), c(0.1,-0.1)) 	lines(c(0.45, 0.45), c(0.1,-0.1)) 	lines(c(0.55, 0.55), c(0.1,-0.1)) 	lines(c(0,-0.2), c(0.2,0.2)) 	lines(c(-0.2,-0.2), c(0.2,0)) }  dev.off() 

我，本作品著作权人，特此采用以下许可协议发表本作品：

	本作品采用知识共享CC0 1.0 通用公有领域贡献许可协议授权。
	采用本宣告发表本作品的人，已在法律允许的范围内，通过在全世界放弃其对本作品拥有的著作权法规定的所有权利（包括所有相关权利），将本作品贡献至公有领域。您可以复制、修改、传播和表演本作品，将其用于商业目的，无需要求授权。 http://creativecommons.org/publicdomain/zero/1.0/deed.enCC0Creative Commons Zero, Public Domain Dedicationfalsefalse