hi all why does the following not work???
this was someone elses code and i couldnt explain why it doesn't work. m=matrix(c(0,0),2,1) v=matrix(c(1,0,0,1),2,2) Y=function(X1,X2,mu=m,V=v) { X=matrix(c(X1,X2),2,1) a=(1/((2*pi)*sqrt(det(V))))*exp((-0.5)*(t(X-mu)%*%solve(V)%*%(X-mu))) a[1] } x1=seq(-1,1) x2=x1 Z=outer(x1,x2,FUN="Y",mu=m,V=v) persp(x1,x2,Z) my code: BINORMAL<-function(varx=1,vary=1,covxy=0,meanx=0,meany=0) { #the following function plots the density of a bi variate normal distribution covXY<-matrix(c(varx,covxy,covxy,vary),2,2) A<-solve(covXY) #up<-max(meanx+4*varx^.5,meanx-4*varx^.5,meany+4*vary^.5,meany-4*vary^.5) #x <- seq(-up,up,length=50) #y <- x x <- seq(meanx-3*varx^.5,meanx+3*varx^.5,length=50) y <- seq(meany-3*vary^.5,meany+3*vary^.5,length=50) f <- function(x,y,...) { detA<-det(A) quadForm<-A[1,1]*(x-meanx)^2+2*A[1,2]*(x-meanx)*(y-meany)+A[2,2]*(y-meany)^2 K<-sqrt(detA)/(2*pi) exp(-0.5*quadForm)*K } z <- outer(x, y, f) par(mfrow=c(1,2)) persp(x, y, z,theta = 30, phi = 30,col="white",main="BI-VARIATE NORMAL DISTRIBUTION") contour(x,y,z,main=paste("xy plot, corr(X,Y)= ",(covxy/(varx*vary)^.5))) print("NOTE -sqrt(varx*vary)<=covxy<=sqrt(varx*vary)") #print(A) } BINORMAL(varx=1,vary=1,covxy=0,meanx=0,meany=0) thanx /allan ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html