parametric-equations

I have the following survreg model: Call: survreg(formula = Surv(time = (ev.time), event = ev) ~ age, data = my.data, dist = "weib") Value Std. Error z p (Intercept) 4.0961 0.5566 7.36 1.86e-13 age 0.0388 0.0133 2.91 3.60e-03 Log(scale) 0.1421 0.1208 1.18 2.39e-01 Scale= 1.15 Weibull distribution I would like to plot the hazard function and the survival function based on the above estimates. I don't want to use predict() or pweibull() (as presented here Parametric Survival or here SO question . I would like to use the curve() function. Any ideas how I can accomplish this? It seems the Weibull

Suppose that (x(t),y(t)) has polar coordinates(√t,2πt). Plot (x(t),y(t)) for t∈[0,10]. There is no proper function in R to plot with polar coordinates. I tried normal plot by giving, x=√t & y=2πt. But resultant graph was not as expected. I got this question from "Introduction to Scientific Programming and Simulation using r"and the book is telling the plot should be spiral. Make a sequence: t <- seq(0,10, len=100) # the parametric index # Then convert ( sqrt(t), 2*pi*t ) to rectilinear coordinates x = sqrt(t)* cos(2*pi*t) y = sqrt(t)* sin(2*pi*t) png("plot1.png");plot(x,y);dev.off() That doesn

Background Looking to create interesting video transitions (in grayscale). Problem Given equations that represent a closed, symmetrical shape, plot the outline and concentrically shade the shape towards its centre. Example Consider the following equations: x = 16 * sin(t)^3 y = 13 * cos(t) - 5 * cos(2 * t) - 2 * cos(3 * t) - cos(4 * t) t = [0:2 * pi] When plotted: When shaded, it would resemble (not shown completely shaded, but sufficient to show the idea): Notice that shading is darkest on the outside (e.g., #000000 RGB hex), then lightens as it fills to the centre. The centre would be a

Possible Duplicate: Equation-driven smoothly shaded concentric shapes How could I plot a symmetrical heart in R like I plot a circle (using plotrix) or a rectangle? I'd like code for this so that I could actually do it for my self and to be able to generalize this to similar future needs. I've seen even more elaborate plots than this so it's pretty doable, it's just that I lack the knowledge to do it. This is an example of plotting a "parametric equation", i.e. a pairing of two separate equations for x and y that share a common parameter. You can find many common curves and shapes that can be