R version 3.0.2 (2013-09-25) -- "Frisbee Sailing"
Copyright (C) 2013 The R Foundation for Statistical Computing
Platform: i686-pc-linux-gnu (32-bit)

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> x <- c(4.8,5.4,6,6,4,6,4.2,4.2,4.2,4,4.6,5.7,3.8,4.8,4.2,4,5.4,4.6,4,4.4,5,5.4,5.2,4.4,4,3.4,4.4,4,4.4,4.4,4,4.8,4,4,5,4,3.4,4,5.4,4.2,4,5.6,4.8,4.4,4.6,4,5.2,4.8,4.6,4,4.2,4.6,4.4,5,5,4,3.8,5.2,4.2,4.4,4.2,6,4.8,4,4.4,4,4.8,4.8,5.6,6,4,4.2,5,4.4,4.2,4.6,4.4,4,4,4,4.2,4,5,4.2,5.4,4,6,3.8,5,4.4,5,4.4,5,4.2,4.6,5)
> par1 = '0'
> xlab = 'Survey Score'
> main = 'Maternal IQ'
> par1 <- '0'
> #'GNU S' R Code compiled by R2WASP v. 1.2.291 ()
> #Author: root
> #To cite this work: Ian E. Holliday, 2012, Histogram,  QQplot and Density Plot (v1.0.1) in Free Statistics Software (v$_version), Office for Research Development and Education, URL http://www.wessa.net/Ian.Holliday/rwasp_Distributional Plots.wasp/
> #Source of accompanying publication: 
> #
> x <- x[!is.na(x)]
> postscript(file="/var/wessaorg/rcomp/tmp/1rbjz1385419874.ps",horizontal=F,onefile=F,pagecentre=F,paper="special",width=8.3333333333333,height=5.5555555555556) 
> par1 <- as.numeric(par1)
> myhist<-hist(x, breaks=par1, col=2, xlab=xlab, main=main)
Error in hist.default(x, breaks = par1, col = 2, xlab = xlab, main = main) : 
  invalid number of 'breaks'
Calls: hist -> hist.default
Execution halted