Alternatively you could grab the Statistics supplement from the application center, it uses the same Standard deviation calculation that most other softwares use to calculate the standard deevs. http://www.maplesoft.com/applications/view.aspx?SID=4679

Save the .lib and .ind files in your user directory

For example in my Maple12 folder I saved it under users/statsupp/

restart;

libname:="c:/Program Files/Maple 12/Users/statsupp/",libname

with(stat)

[Anova1,Anova2m,Anova2s,AnovaBeta,BernoulliCDF,BernoulliPDF,BernoulliS,BetaCDF,BetaP,BetaPDF,BetaS,

BinomialCDF,BinomialPDF,BinomialS,BivariateNormalPDF,BivariateNormalS,BoxWhisker,CauchyPDF,CauchyS,

ChisquareCDF,ChisquareFit,ChisquareP,ChisquarePDF,ChisquareS,ClassFreq,ConfIntAvLen,ConfIntMean,

ConfIntPlot,ConfIntProp,ConfIntSuc,ConfIntVar,Contingency,ContinuousS,Convolution,Correlation,Craps,Die,

DiscUniformS,DiscreteS,DoubleExponentialPDF,ExponentialCDF,ExponentialP,ExponentialPDF,ExponentialS,

ExponentialSumS,FCDF,FP,FPDF,FS,FastCraps,Freq,GBCDF,GBDPDF,GBP,GammaCDF,GammaP,GammaPDF,

GammaS,GeometricCDF,GeometricPDF,GeometricS,GraphRandWalk,GraphRandWalk2,Histogram,

HypergeometricPDF,HypergeometricS,KSFit,Kurtosis,LinReg,Locate,LogisticPDF,LogisticS,MakeRandom,

MarginalRelFreq,Max,Mean,Median,MedianTest,Min,N01S,NegBinomialCDF,NegBinomialPDF,NegBinomialS,

NormTransVarS,NormalCDF,NormalMeanS,NormalMedianS,NormalP,NormalPDF,NormalS,NormalSumS,

NormalVarianceS,Ogive,Percentile,PlotDiscCDF,PlotEmpCDF,PlotEmpPDF,PlotPolyReg,PlotRunningAverage,

PoissonCDF,PoissonPDF,PoissonS,PolyReg,ProbHist,QQ,QQFit,RNG,RandWalk,RandWalk2,Range,RegAnal,

RegBand,Residuals,RunTest,RunningSum,ScatPlot,ScatPlotLine,SignTest,Skewness,StDev,StemLeaf,TCDF,

TP,TPDF,TS,TimePlot,UniformCDF,UniformMeanS,UniformMedianS,UniformP,UniformPDF,UniformS,

UniformSumS,Variance,WeibullPDF,Wilcoxon,Wilcoxon2,XbarChart,rng]

a:=[[3,7],[2,13]]:

StDev(a)

evalf(%,15)

0.489360484929593