bool LeastSquares1D::SolveUnweighted()
{
assert(x.n == y.n);
assert(x.n >= 2);
Real sxx,syy,sxy;
Real xmean = Mean(x);
Real ymean = Mean(y);
sxx = syy = sxy = 0;
for(int i=0;i<x.n;i++) {
sxx += Sqr(x(i) - xmean);
syy += Sqr(y(i) - ymean);
sxy += (x(i) - xmean)*(y(i) - ymean);
}
if(sxx == 0) { //vertical line!
b = xmean;
a = Inf;
stda = stdb = 0;
corrCoeff = 1;
return true;
}
a = sxy / sxx;
b = ymean - b*xmean;
if(x.n == 2) {
stda = stdb = 0;
corrCoeff = 1;
return true;
}
Real s = Sqrt((syy - b*sxy)/(x.n-2));
stda = s / Sqrt(sxx);
stdb = s*Sqrt(One/(Real)x.n + Sqr(xmean)/sxx);
return true;
}
void MassUmbalances(OpenSMOKE_KPP_ReactorNetwork& network)
{
BzzVector umbalances(network.NumberOfReactors());
for(int k=1;k<=network.NumberOfReactors();k++)
umbalances[k] = fabs(network.reactors(k).MassUmbalance());
BzzVector massFlowIn(network.NumberOfReactors());
for(int k=1;k<=network.NumberOfReactors();k++)
massFlowIn[k] = fabs(network.reactors(k).MassFlowIn());
cout << endl;
cout << "// *********************************************************** // " << endl;
cout << "// UMBALANCE ANALYSIS // " << endl;
cout << "// *********************************************************** // " << endl;
cout << setw(20) << left << "Max umbalance:";
cout << setw(16) << left << umbalances.Max();
cout << endl;
cout << setw(20) << left << "Mean umbalance:";
cout << setw(16) << left << Mean(umbalances);
cout << endl;
cout << setw(20) << left << "Max in flow:";
cout << setw(16) << left << massFlowIn.Max();
cout << endl;
cout << setw(20) << left << "Min in flow:";
cout << setw(16) << left << massFlowIn.Min();
cout << endl;
cout << setw(20) << left << "Mean in flow:";
cout << setw(16) << left << Mean(massFlowIn);
cout << endl;
}
bool LeastSquares1D::SolvePerpendicular()
{
//minimize sum_i { (yi - a*xi - b)^2 / (1+b^2) }
assert(x.n == y.n);
assert(x.n >= 2);
Real sxx,syy,sxy;
Real xmean = Mean(x);
Real ymean = Mean(y);
sxx = syy = sxy = 0;
for(int i=0;i<x.n;i++) {
sxx += Sqr(x(i) - xmean);
syy += Sqr(y(i) - ymean);
sxy += (x(i) - xmean)*(y(i) - ymean);
}
Real den = (x.n*xmean*ymean - dot(x,y));
if(FuzzyZero(den)) {
cerr<<"Warning, denominator is close to zero"<<endl;
}
Real B = (syy - sxx) / den;
a = -B + Sqrt(Sqr(B)+1);
b = ymean - xmean*b;
cerr<<"Warning, don't know how to calculate std errors for perpendicular least-squares"<<endl;
stda = stdb = 0;
corrCoeff = 1;
return true;
}
void FilterStream(FILTER *FIL, FILE *OUT){
int64_t n = 1;
ENTP val = Mean(FIL, 0);
int region = val < FIL->threshold ? LOW_REGION : HIGH_REGION, cmp = 0;
uint64_t initPosition = 1;
uint64_t lastPosition = n;
for(n = 1 ; n < FIL->nEntries ; ++n){
if(n % FIL->drop == 0){
if((val = Mean(FIL, n)) >= FIL->threshold){
if(region == LOW_REGION){
region = HIGH_REGION;
cmp = SelfSimilarity(FIL->bases, initPosition, n);
fprintf(OUT, "%"PRIu64":%"PRIu64"\t%u\n", initPosition, n, cmp);
}
}
else{ // val < threshold ====> LOW_REGION
if(region == HIGH_REGION){
region = LOW_REGION;
initPosition = n;
}
}
lastPosition = n;
}
}
if(region == LOW_REGION){
cmp = SelfSimilarity(FIL->bases, initPosition, n);
fprintf(OUT, "%"PRIu64":%"PRIu64"\t%u\n", initPosition, lastPosition, cmp);
}
}
//This tells you how corrolated your x and y are. A straight line, at any non0 angle, give you a corrolation of 1.
//If this is nonzero, it means the points vary more in one direction than in another. This number should be close to 0.
double PearsonProductMomentCorrelation(double x[], double y[], int size)
{
//Base case
if( size<=1 )
{
return 0;
}
double ans;
double xmean;
double ymean;
xmean = Mean(x, size);
ymean=Mean(y, size);
int i;
double s;
double xv;
double yv;
double t1;
double t2;
s = 0;
xv = 0;
yv = 0;
for(i=0; i<size; i++)
{
t1 = abs(x[i]-xmean);
t2 = abs(y[i]-ymean);
xv = xv+sqrt(t1);
yv = yv+sqrt(t2);
s = s+t1*t2;
}
ans = s/sqrt(xv)*sqrt(yv);
return ans;
}
TEST(Util, NormalSampleTest) {
VReal tmp;
for (int i = 0; i < 1000000; i++) {
tmp.push_back(NormalSample() / 100);
}
EXPECT_LT(std::abs(0.0 - Mean(tmp)), 0.00001);
EXPECT_LT(std::abs(0.0001 - Var(tmp)), 0.00001);
VVVReal tmp2;
RandomInit(100, 100, 100, &tmp2);
EXPECT_LT(std::abs(0.0 - Mean(tmp2)), 0.00001);
EXPECT_LT(std::abs(0.0001 - Var(tmp2)), 0.00001);
}
//Histogram *Unser(Image *img)
float *Unser(Image *img)
{
Histogram *h = NULL;
float sum[4][511], dif[4][511], *val=NULL;
float mean, contrast, correlation;
int i;
val = (float*) calloc(SIZE,sizeof(float));
ComputeHistograms(img, sum, dif);
for (i=0; i<4; i++){
mean = Mean(sum[i]);
val[i * 8 + 0] = mean;
contrast = Contrast(dif[i]);
val[i * 8 + 1] = contrast;// / 255.0;
correlation = Correlation(sum[i], mean, contrast);
val[i * 8 + 2] = (correlation);// + 32512.5) / 255.0;
val[i * 8 + 3] = Energy(sum[i], dif[i]);// * 255.0 ;
val[i * 8 + 4] = Entropy(sum[i], dif[i]);// * 255.0 / 5.4168418;
val[i * 8 + 5] = Homogeneity(dif[i]);// * 255.0;
val[i * 8 + 6] = MaximalProbability(sum[i]);// * 255.0;
val[i * 8 + 7] = StandardDeviation(contrast, correlation);// *sqrt(2);
}
//h = CreateHistogram(SIZE);
//LinearNormalizeHistogram(h->v, val, 255.0, SIZE);
//return(h);
return(val);
}
/*---------------------------------------------------------------------------*/
void PrintNormMatch(FILE *File,
int NumParams,
PROTOTYPE *Proto,
FEATURE Feature) {
/*
** Parameters:
** File open text file to dump match debug info to
** NumParams # of parameters in proto and feature
** Proto[] array of prototype parameters
** Feature[] array of feature parameters
** Globals: none
** Operation: This routine dumps out detailed normalization match info.
** Return: none
** Exceptions: none
** History: Wed Jan 2 09:49:35 1991, DSJ, Created.
*/
int i;
FLOAT32 ParamMatch;
FLOAT32 TotalMatch;
for (i = 0, TotalMatch = 0.0; i < NumParams; i++) {
ParamMatch = ((ParamOf (Feature, i) - Mean (Proto, i)) /
StandardDeviation (Proto, i));
fprintf (File, " %6.1f", ParamMatch);
if (i == CharNormY || i == CharNormRx)
TotalMatch += ParamMatch * ParamMatch;
}
fprintf (File, " --> %6.1f (%4.2f)\n",
TotalMatch, NormEvidenceOf (TotalMatch));
} /* PrintNormMatch */
/*
Function Name :: StandarDeviation
input :: pointer to bag
return's :: float
This function will take in a bag as input.
This function will then calculate the standard deviation of the data in the bag.
Using the formula for the standard deviation of a normal distribution.
Return the standard deviation calculated.
standard deviation = sqrt((sum of square of all deviation/(number of elemnts -1)))
*/
float StandardDeviation(bag *bg)
{
int length = getsize(bg);
int i;
float mean = Mean(bg);
float sum = 0;
float difference = 0;
data *dat = NULL;
for(i=0;i< length;i++)
{
dat = getItem(bg,i);
difference = (mean - dat->val);
if(difference < 0)
{
difference = (-1 * difference);
}
sum = sum + (difference *difference);
}
float deviation = (float)sum/(length-1);
deviation = sqrtf(deviation);
return (deviation);
}
TEST(Util, MeanTest) {
VReal tmp;
tmp.push_back(1);
tmp.push_back(2);
tmp.push_back(3);
EXPECT_DOUBLE_EQ(2, Mean(tmp));
}
/// <summary>
/// Tests if the difference between two measurement histories is statistically significant to
/// make a hill climbing decision.
/// </summary>
/// <remarks>
/// A two sided test is used.
/// </remarks>
/// <param name="pMeasuredHistory">
/// The pointer to second measurement history.
/// </param>
/// <param name="significanceLevel">
/// The significance level in percent. Accepts 1 through 10.
/// </param>
/// <returns>
/// -1 - second history is larger than this history
/// 0 - statistically identical
/// 1 - this history is larger than second history
/// </returns>
int HillClimbing::MeasuredHistory::SignificanceTest(MeasuredHistory * pMeasuredHistory, const int significanceLevel)
{
const int critSize = 10;
double critArray[critSize] = { 2.576, 2.3263, 2.17, 2.05, 1.96, 1.88, 1.81, 1.75, 1.70, 1.64 };
double thisVariance = this->VarianceMean();
double thisMean = Mean();
double secondVariance = pMeasuredHistory->VarianceMean();
double secondMean = pMeasuredHistory->Mean();
_CONCRT_ASSERT(significanceLevel > 0 && significanceLevel <= 10); // Invalid significance level
int result = (int) sign(thisMean - secondMean);
if (thisVariance > 0 && secondVariance > 0)
{
double pooledVar = thisVariance / Count() + secondVariance / pMeasuredHistory->Count();
double testStatistic = (thisMean - secondMean) / sqrt(pooledVar);
double critVal = critArray[significanceLevel-1];
double absVal = abs(testStatistic);
if (absVal < critVal)
{
result = 0;
}
}
return result;
}
void plot_data (int color)
{
int pix_num,bckgrd_satus;
double bckgrd_val;
GetCtrlVal (ERG_panel, ERG_panel_bckgrd_sub, &bckgrd_satus);
if (bckgrd_satus==1)
{
GetCtrlVal (ERG_panel, ERG_panel_bckgrd, &pix_num);
Mean (&data2fit[pix_num-50], 100, &bckgrd_val);
j=0;
while (j<10000)
{
buffer[j] = data2fit[j]-bckgrd_val;
j++;
}
}
else
{
j=0;
while (j<10000)
{
buffer[j] = data2fit[j];
j++;
}
}
PlotY (ERG_panel, ERG_panel_scope, buffer, 10000,VAL_DOUBLE , VAL_THIN_LINE, VAL_EMPTY_SQUARE, VAL_SOLID, 1, MakeColor(color,color,color));
}
void Net::ReadLabels(const mxArray *mx_labels) {
std::vector<size_t> labels_dim = mexGetDimensions(mx_labels);
mexAssert(labels_dim.size() == 2, "The label array must have 2 dimensions");
size_t samples_num = labels_dim[0];
size_t classes_num = labels_dim[1];
mexAssert(classes_num == layers_.back()->length_,
"Labels and last layer must have equal number of classes");
MatCPU labels_norm; // order_ == false
mexGetMatrix(mx_labels, labels_norm);
if (params_.balance_) {
MatCPU labels_mean(1, classes_num);
Mean(labels_norm, labels_mean, 1);
mexAssert(!labels_mean.hasZeros(),
"Balancing impossible: one of the classes is not presented");
MatCPU cpucoeffs(1, classes_num);
cpucoeffs.assign(1);
cpucoeffs /= labels_mean;
classcoefs_.resize(1, classes_num);
classcoefs_ = cpucoeffs;
classcoefs_ /= (ftype) classes_num;
}
labels_.resize(samples_num, classes_num);
labels_.reorder(true, false); // order_ == true;
labels_ = labels_norm;
}
inline
const std::vector<T>
ICR::EnsembleLearning::DeterministicNode<Model,T>::GetMean()
{
std::vector<T> Mean(1, m_Moments[0]);
return Mean;
}
double ChiRand::Skewness() const
{
double mu = Mean();
double sigmaSq = Variance();
double skew = mu * (1 - 2 * sigmaSq);
skew /= std::pow(sigmaSq, 1.5);
return skew;
}
static void chanfunc_CalcStatistics (channelPtr chan)
{
double mean, std_dev, variance, rms, moment, median, mode, min, max;
int err, order, min_i, max_i, intervals;
char newnote[256];
Fmt (chanfunc.note, "");
err = MaxMin1D (chan->readings, chan->pts, &max, &max_i, &min, &min_i);
SetInputMode (chanfunc.p, STATISTICS_MIN, !err);
SetCtrlVal (chanfunc.p, STATISTICS_MIN, min);
SetInputMode (chanfunc.p, STATISTICS_MAX, !err);
SetCtrlVal (chanfunc.p, STATISTICS_MAX, max);
if (err == NoErr)
{
Fmt (chanfunc.note, "%s<Min: %f[e2p5]\n", min);
Fmt (chanfunc.note, "%s[a]<Max: %f[e2p5]\n", max);
}
err = Mean (chan->readings, chan->pts, &mean);
SetInputMode (chanfunc.p, STATISTICS_MEAN, !err);
SetCtrlVal (chanfunc.p, STATISTICS_MEAN, mean);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<Mean: %f[e2p5]\n", mean);
err = StdDev (chan->readings, chan->pts, &mean, &std_dev);
SetInputMode (chanfunc.p, STATISTICS_STDDEV, !err);
SetCtrlVal (chanfunc.p, STATISTICS_STDDEV, std_dev);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<StdDev: %f[e2p5]\n", std_dev);
err = Variance (chan->readings, chan->pts, &mean, &variance);
SetInputMode (chanfunc.p, STATISTICS_VAR, !err);
SetCtrlVal (chanfunc.p, STATISTICS_VAR, variance);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<Variance: %f[e2p5]\n", variance);
err = RMS (chan->readings, chan->pts, &rms);
SetInputMode (chanfunc.p, STATISTICS_RMS, !err);
SetCtrlVal (chanfunc.p, STATISTICS_RMS, rms);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<RMS: %f[e2p5]\n", rms);
GetCtrlVal (chanfunc.p, STATISTICS_ORDER, &order);
err = Moment (chan->readings, chan->pts, order, &moment);
SetInputMode (chanfunc.p, STATISTICS_MOMENT, !err);
SetInputMode (chanfunc.p, STATISTICS_ORDER, !err);
SetCtrlVal (chanfunc.p, STATISTICS_MOMENT, moment);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<Moment: %f[e2p5] (order: %i)\n", moment, order);
err = Median (chan->readings, chan->pts, &median);
SetInputMode (chanfunc.p, STATISTICS_MEDIAN, !err);
SetCtrlVal (chanfunc.p, STATISTICS_MEDIAN, median);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<Median: %f[e2p5]\n", median);
GetCtrlVal (chanfunc.p, STATISTICS_INTERVAL, &intervals);
err = Mode (chan->readings, chan->pts, min, max, intervals, &mode);
SetInputMode (chanfunc.p, STATISTICS_INTERVAL, !err);
SetInputMode (chanfunc.p, STATISTICS_MODE, !err);
SetCtrlVal (chanfunc.p, STATISTICS_INTERVAL, intervals);
SetCtrlVal (chanfunc.p, STATISTICS_MODE, mode);
if (err == NoErr) Fmt (chanfunc.note, "%s[a]<Mode: %f[e2p5] (intervals: %i)\n", mode, intervals);
}
CReal CTimeWiener::ModLinRegr(CComplexVector& veccCorrEst)
{
/* Modified linear regression to estimate the "sigma" of the Gaussian
correlation function */
/* Get vector length */
int iVecLen = Size(veccCorrEst);
/* Init vectors and variables */
CReal rSigmaRet;
CRealVector Tau(iVecLen);
CRealVector Z(iVecLen);
CRealVector W(iVecLen);
CRealVector Wmrem(iVecLen);
CReal Wm, Zm;
CReal A1;
/* Generate the tau vector */
for (int i = 0; i < iVecLen; i++)
Tau[i] = (CReal) (i * iScatPilTimeInt);
/* Linearize acf equation: y = a * exp(-b * x^2)
z = ln(y); w = x^2
-> z = a0 + a1 * w */
Z = Log(Abs(veccCorrEst));
W = Tau * Tau;
Wm = Mean(W);
Zm = Mean(Z);
Wmrem = W - Wm; /* Remove mean of W */
A1 = Sum(Wmrem * (Z - Zm)) / Sum(Wmrem * Wmrem);
/* Final sigma calculation from estimation and assumed Gaussian model */
rSigmaRet = (CReal) 0.5 / crPi * sqrt((CReal) -2.0 * A1) / Ts;
/* Bound estimated sigma value */
if (rSigmaRet > rSigmaMax)
rSigmaRet = rSigmaMax;
if (rSigmaRet < LOW_BOUND_SIGMA)
rSigmaRet = LOW_BOUND_SIGMA;
return rSigmaRet;
}
double NakagamiDistribution::Skewness() const
{
double thirdMoment = lgammaShapeRatio;
thirdMoment -= 1.5 * Y.GetLogRate();
thirdMoment = (m + 0.5) * std::exp(thirdMoment);
double mean = Mean();
double variance = Variance();
return (thirdMoment - mean * (3 * variance + mean * mean)) / std::pow(variance, 1.5);
}
double Statistics::StdDev(Image& Source, double& mean)
{
mean = Mean(Source);
Kernel(reduce_stddev, In(Source), Out(), *m_PartialResultBuffer, Source.Step(), Source.Width(), Source.Height(), float(mean));
m_PartialResultBuffer->Read(true);
return sqrt(ReduceMean(m_PartialResult));
}
double UnivariateDistribution<T>::ThirdMoment() const
{
double mean = Mean();
double variance = Variance();
double skewness = Skewness();
double moment = skewness * std::sqrt(variance) * variance;
moment += mean * mean * mean;
moment += 3 * mean * variance;
return moment;
}
double StandardDeviation(std::vector<double> vars)
{
double stddev = 0;
double mean = Mean(vars);
for (unsigned int i=0; i<vars.size(); ++i) {
stddev += Square(vars.at(i) - mean);
}
stddev = stddev/vars.size();
return sqrt(stddev);
}
double ChiRand::ExcessKurtosis() const
{
double mu = Mean();
double sigmaSq = Variance();
double sigma = std::sqrt(sigmaSq);
double skew = Skewness();
double kurt = 1.0 - mu * sigma * skew;
kurt /= sigmaSq;
--kurt;
return 2 * kurt;
}
int main()
{
double scores[MaxJudges];
int nJudges;
printf("Enter the number of judges: ");
nJudges=GetInteger();
if(nJudges>MaxJudges) Error("Too many judges");
ReadAllScores(scores,nJudges);
printf("The average score is %.2f\n",Mean(scores,nJudges));
}
// Only the diagonal of the covariance matrix.
Vector3f SensorFilter::Variance() const
{
Vector3f mean = Mean();
Vector3f total = Vector3f(0.0f, 0.0f, 0.0f);
for (int i = 0; i < Count; i++)
{
total.x += (Elements[i].x - mean.x) * (Elements[i].x - mean.x);
total.y += (Elements[i].y - mean.y) * (Elements[i].y - mean.y);
total.z += (Elements[i].z - mean.z) * (Elements[i].z - mean.z);
}
return total / (float) Count;
}
double NakagamiDistribution::ExcessKurtosis() const
{
double mean = Mean();
double secondMoment = SecondMoment();
double thirdMoment = ThirdMoment();
double fourthMoment = FourthMoment();
double meanSq = mean * mean;
double variance = secondMoment - meanSq;
double numerator = fourthMoment - 4 * thirdMoment * mean + 6 * secondMoment * meanSq - 3 * meanSq * meanSq;
double denominator = variance * variance;
return numerator / denominator - 3.0;
}
void MyOpenSMOKE_SolidRegression::Prepare()
{
ChangeDimensions(numTotal, &temperatures_global);
ChangeDimensions(numTotal, &utemperatures_global);
ChangeDimensions(numTotal, &pressures_Gas_global);
int k=1;
for(int i=1;i<=nCases;i++)
{
for(int j=1;j<=experiments[i].nPoints;j++)
{
temperatures_global[k] = experiments[i].temperature;
utemperatures_global[k] = 1./temperatures_global[k];
pressures_Gas_global[k] = experiments[i].pressure;
k++;
}
}
TMeanGlobal = Mean(temperatures_global);
PGasMeanGlobal = Mean(pressures_Gas_global);
C2 = -1./TMeanGlobal;
C3 = pressures_Gas_global.Norm2();
BzzVector auxiliar_vector = utemperatures_global;
for(k=1;k<=numTotal;k++) auxiliar_vector[k] += C2;
C1 = 1./auxiliar_vector.Norm2();
cout << "Tmin: " << temperatures_global.Min() << " K" << endl;
cout << "Tmax: " << temperatures_global.Max() << " K" << endl;
cout << "Tmean: " << TMeanGlobal << " K" << endl;
cout << "PGasmin: " << pressures_Gas_global.Min() << " atm" << endl;
cout << "PGasmax: " << pressures_Gas_global.Max() << " atm" << endl;
cout << "PGasmean: " << PGasMeanGlobal << " atm" << endl;
cout << "C1: " << C1 << " K" << endl;
cout << "C2: " << C2 << " 1/K" << endl;
cout << "C3: " << C3 << " atm" << endl;
}
void RunningStats::Print(FILE * pFile, const char * header) const
{
fprintf (pFile, "\n%s\n", header);
fprintf (pFile, "NumDataValues: %ld\n", NumDataValues());
fprintf (pFile, "Mean: %f\n", Mean());
fprintf (pFile, "Variance: %f\n", Variance());
fprintf (pFile, "StandardDeviation: %f\n", StandardDeviation());
fprintf (pFile, "Skewness: %f\n", Skewness());
fprintf (pFile, "Kurtosis: %f\n", Kurtosis());
fprintf (pFile, "Maximum: %f\n", Maximum());
fprintf (pFile, "Minimum: %f\n", Minimum());
return;
}
double CBlob::StdDev( IplImage *image )
{
// it is calculated?
/* if( m_stdDevGray != -1 )
{
return m_stdDevGray;
}
*/
// call mean calculation (where also standard deviation is calculated)
Mean( image );
return m_stdDevGray;
}
/******************************************************************************\
* Phase lock loop (PLL) *
\******************************************************************************/
void CPLL::Process(CRealVector& vecrIn /* in/out */)
{
/* Mix it down to zero frequency */
cvecLow = vecrIn;
Mixer.Process(cvecLow);
/* Complex loop filter */
rvecRealTmp = Filter(rvecB, rvecA, Real(cvecLow), rvecZReal);
rvecImagTmp = Filter(rvecB, rvecA, Imag(cvecLow), rvecZImag);
/* Calculate current phase for GUI */
rCurPhase = Angle(CComplex(Mean(rvecRealTmp), Mean(rvecImagTmp)));
/* Average over entire block (only real part) */
const CReal rOffsEst = Mean(rvecRealTmp);
/* Close loop */
rNormCurFreqOffsetAdd = PLL_LOOP_GAIN * rOffsEst;
/* Update mixer */
Mixer.SetMixFreq(rNormCurFreqOffset + rNormCurFreqOffsetAdd);
}
// Standard deviation of a set of probabilities
static double Sigma(ub4 minx,ub4 maxs) {
register ub4 i,dv;
double m, t=0.0;
double d[MODU];
dv = maxs-minx+1;
m = Mean(minx,maxs);
for (i=minx; i<=maxs; i++)
d[i] = pow((prob[i]-m),2);
// variance
for (i=minx; i<=maxs; i++) t += d[i];
m = (double) t/dv;
return sqrt(m);
}