{
"cells": [
{
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"id": "c0cb7354",
"metadata": {},
"source": [
"# gr002_errors\n",
"[gr03_err2gr.C](https://root.cern/doc/master/gerrors2_8C.html) tutorial\n",
"\n",
"See the [TGraphErrors documentation](https://root.cern/doc/master/classTGraphErrors.html)\n",
"\n",
"\n",
"\n",
"**Author:** Rene Brun \n",
"This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, May 19, 2026 at 08:37 PM."
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "1b95bc55",
"metadata": {
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"execution": {
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"shell.execute_reply": "2026-05-19T20:37:41.797677Z"
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"outputs": [],
"source": [
"TCanvas *c1 = new TCanvas(\"c1\",\"A Simple Graph with error bars\",200,10,700,500);\n",
"\n",
"c1->SetGrid();\n",
"c1->GetFrame()->SetBorderSize(12);"
]
},
{
"cell_type": "markdown",
"id": "3941d342",
"metadata": {},
"source": [
"We will use the constructor requiring: the number of points, arrays containing the x-and y-axis values, and arrays with the x- andy-axis errors"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "f6d33209",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:37:42.053385Z"
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"outputs": [],
"source": [
"const Int_t n = 10;\n",
"Float_t x[n] = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};\n",
"Float_t y[n] = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};\n",
"Float_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};\n",
"Float_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};"
]
},
{
"cell_type": "markdown",
"id": "0db7d508",
"metadata": {},
"source": [
"If all x-axis errors should zero, just provide a single 0 in place of ex"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "df8b56e7",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:37:42.281706Z"
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},
"outputs": [],
"source": [
"TGraphErrors *gr = new TGraphErrors(n,x,y,ex,ey);\n",
"\n",
"gr->SetTitle(\"TGraphErrors Example\");\n",
"gr->SetMarkerColor(4);\n",
"gr->SetMarkerStyle(21);"
]
},
{
"cell_type": "markdown",
"id": "cbeca193",
"metadata": {},
"source": [
"To draw in a new/empty canvas or pad, include the option \"A\" so that the axes are drawn (leave it out if the graph is to be drawn on top of an existing plot"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "5293ddf5",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:37:42.293220Z",
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"shell.execute_reply": "2026-05-19T20:37:42.503919Z"
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"source": [
"gr->Draw(\"ALP\");\n",
"\n",
"c1->Update();"
]
},
{
"cell_type": "markdown",
"id": "d52898cb",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "bd2aa962",
"metadata": {
"collapsed": false,
"execution": {
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],
"source": [
"%jsroot on\n",
"gROOT->GetListOfCanvases()->Draw()"
]
}
],
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"kernelspec": {
"display_name": "ROOT C++",
"language": "c++",
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