Getting numerical values from points of a graph

Questions
1

Hello to everyone! Could anyone tell me how to get the numbers corresponded to a certain position in a graphic, like the peaks or when it crosses the abscissa?

2

By “graphic” do you mean an image? If so, please attach an example to your post.

If you know the function corresponding to the graph then you can try solving f == 0 to get the roots (crossing abscissa) and solving for f' == 0 to get the local minima/maxima or point of inflection.

3

For instance:

sq=Table[j,{j,1000}]
n=Select[sq,PrimeQ,(100)]
sq2=Table[k,{k,100}]
n3=sq2*-1
r=Table[k1,{k1,100}]
f=(((Pi+1)*r)*Sqrt[(-2*Pi*r)/((Pi+1)*r)])/((Sqrt[(2*Pi*r)^2+2*Pi*r/n]))
bb=Im[f]
s1cc=(((1)+bb*r*Sqrt[-1])+((0)+bb*r*Sqrt[-1]))/2
zz=-n3
zx=n
x1c1c=\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(zx = 1\), \(100\)]\((1/zx*zx^s1cc)\)\)
jj=Sum[1/zx*zx^s1cc,{2,541}]
u=N[jj]
k=N[x1c1c]
x1c1c2=\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(zz = 1\), \(100\)]\((1/zz*zz^s1cc)\)\)
kk=N[x1c1c2]
x1cc1=Re[x1c1c]
x1cc2=Im[x1c1c]
x1c=Re[x1c1c2]
x1c2=Im[x1c1c2]

proof2=(x1c-x1c2)/(x1c+x1c2)
proof=(x1cc1-x1cc2)/(x1cc1+x1cc2)
g=proof-proof2
ListLinePlot[proof]
ListLinePlot[proof2]
ListLinePlot[g]

A PROVA DE RIEMANN NÚMEROS NÃO TIRIVIAIS CORRELACIONADOS0002.jpg
A PROVA DE RIEMANN NÚMEROS NÃO TIRIVIAIS CORRELACIONADOS0002.jpg960×663 88.5 KB

4

The code above does not evaluate correctly

Sum::itraw: Raw object 2 cannot be used as an iterator.

Sum::vloc: The variable 2 cannot be localized so that it can be
assigned to numerical values.

For a list of values, try FindPeaks and CrossingDetect. The latter may not satisfy your requirements.

proofN = proof // N;
peaks = FindPeaks[proofN];
zeros = CrossingDetect[proofN]*Range@Length@proofN // Thread[{#, 0}] & // DeleteCases[{0, 0}];

ListLinePlot[proofN,
 PlotRange -> All,
 Epilog -> {Red, Point@peaks, Blue, Point@zeros},
 ImageSize -> Large]

10246plot.png
10246plot.png720×439 31.5 KB

5

THANK YOU SO MUCH ROHIT!!! I never heard of those commands.

6

If anyone know how to get the values for x the abscissa where those points and peaks are, I would thank so much.

7

Take a look at the value of peaks and zeros, they are lists of pairs where each pair is an x, y coordinate.

8

Thank you once again I have taken a look at it I just typed N[peaks] and N[zeros], thank you so much God bless you!!!

9

Right-Click on the (2D) graphic and click on GetCoordinates. Left-Click on a point and save the coordinates with Ctrl-C