Hi, I’d like to have in the box of the histograms the standard deviation value (not the RMS); I wrote:

` hene->GetStdDev();`

as I read here root.cern.ch/doc/master/classTH1.html, but compiling I’ve the error:

How to resolve?

Thanks

Hi, I’d like to have in the box of the histograms the standard deviation value (not the RMS); I wrote:

` hene->GetStdDev();`

as I read here root.cern.ch/doc/master/classTH1.html, but compiling I’ve the error:

How to resolve?

Thanks

Actually, TH1::GetRMS returns the “Standard Deviation (Sigma) of the distribution (not RMS)”.

You need ROOT 5.34/05 or newer for the TH1::GetStdDev method.

[quote=“Pepe Le Pew”]

You need ROOT 5.34/05 or newer for the TH1::GetStdDev method.[/quote]

Hi Pepe, I use 5.34.36, so what do I do? can I use the RMS value as a standard deviation or must I do other to have the standard deviation?

Thanks

It seems to me that, in line 1028 of your “mycorsplot.c”, you have something like (missing “()” in the end):

`hene->GetStdDev`

instead of:

`hene->GetStdDev()`

[quote=“Pepe Le Pew”]It seems to me that, in line 1028 of your “mycorsplot.c”, you have something like (missing “()” in the end):

hene->GetStdDev

instead of:

hene->GetStdDev()[/quote]

Hi pepe and thanks…I looked the code…but it is written:

with an appropriate version of ROOT it works fine:

```
$ root
*******************************************
* *
* W E L C O M E to R O O T *
* *
* Version 5.34/37 6 April 2016 *
* *
* You are welcome to visit our Web site *
* http://root.cern.ch *
* *
*******************************************
root [0] cout << hpx->GetStdDev() << endl;
0.99785
root [1]
```

Hi couet, I’ve root 5.34.36…

PS. I tried again…I don’t know the reason but today I don’t have error but it doesn’t write the value in the statistical box…I tried to write `cout << hene->GetStdDev() << endl;`

, is it possible to add it in the statistical box? thanks

Hi pepe…I looked the link…but it wasn’t what I mean…

I’d like to have something like this

as you can see, in the statistical box there is writtene STD DEV.

ps. pepe you have a private message.

By default, ROOT 6 writes “Std Dev” while ROOT 5 writes “RMS” (but it is the “standard deviation”).

For ROOT 5, you can edit the “`${ROOTSYS}/etc/system.rootrc`

” file (or create you own “`${HOME}/.rootrc`

” file):

```
Hist.Stats.RMS: Std Dev
Hist.Stats.RMSX: Std Dev x
Hist.Stats.RMSY: Std Dev y
Hist.Stats.RMSZ: Std Dev z
```

Thanks pepe!

how did you get the straight line pls? graph 4

Hi! that pic is just an example that I found…I didn’t make it! However the straight line is a fit.

I write you some pieces of a macro that I used to fit a graph.

```
gStyle->SetOptFit();
TF1 *fitspettro = new TF1("fitspettro", "[0] * TMath::Power(x, -[1])", 1, 1e3);
fitspettro->SetParameters(1.0, 2.0);
fitspettro->SetParName(0,"c");
fitspettro->SetParName(1,"#gamma");
heneg->Draw();
heneg->Fit("fitspettro");
c2->Update();
```

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Hello everyone,

I have a problem which is related to this topic, I hope you can assist me with.

I have a root file in which I have several histograms and I need to compute the standard deviation on a particular bin over all the histograms. Could you please tell me the steps I should follow?