Showing posts with label chart. Show all posts
Showing posts with label chart. Show all posts

05 August, 2023

Shapes Based On Johan Gielis's Superformula

The Gielis's Superformula is used to model variety of abstract and natural shapes. It finds application in biology, technology, mathematics, and physics.

I'm providing here a small representation of shapes created with my relatively simple VBA macro listed at the end of this post. You can experiment with different values of the parameters a,b,m,n1,n2, and n3 to get all kinds of shapes and find some useful models. To control the resolution of your shapes you can adjust the number of points, nP. Optionally, I've applied some Excel formatting of the plots.

Sub SuperformulaPlot()
'Generates Gielis's Superformula plot
'Calculates X and Y values and assigns them to the chart series
'Creates a 2D scatter plot; no markers

Dim nP As Integer, i As Integer
Dim xVal() As Double, yVal() As Double, theta As Double, r As Double
Dim a As Double, b As Double, m As Double, n1 As Double, n2 As Double, n3 As Double
Dim chartObj As ChartObject
nP = 500    'You can adjust the number of points to increase/decrease the resolution of the curve
a = WorksheetFunction.RandBetween(1, 5) 'Random parameters a,b,m,n1,n2,n3; experiment!
b = WorksheetFunction.RandBetween(1, 5)
m = WorksheetFunction.RandBetween(1, 10)
n1 = WorksheetFunction.RandBetween(1, 10)
n2 = WorksheetFunction.RandBetween(1, 20)
n3 = WorksheetFunction.RandBetween(1, 10)
'a = 1: b = 1: m = 2: n1 = 5: n2 = 5: n3 = 5    'just some default values
ReDim xVal(1 To nP)
ReDim yVal(1 To nP)
For i = 1 To nP
    theta = 2 * WorksheetFunction.Pi * (i - 1) / nP
    r = (Abs(Cos(m * theta / 4) / a) ^ n2 + Abs(Sin(m * theta / 4) / b) ^ n3) ^ (-1 / n1)
    xVal(i) = r * Cos(theta)
    yVal(i) = r * Sin(theta)
Next i
'Create a 2D scatter plot
Set chartObj = ActiveSheet.ChartObjects.Add(Left:=120, Width:=500, Top:=10, Height:=400)
With chartObj.Chart
    .ChartType = xlXYScatterSmoothNoMarkers
    .SeriesCollection(1).Values = yVal      'Add data to the chart
    .SeriesCollection(1).xValues = xVal
    .HasLegend = False
    .HasTitle = True
    .ChartTitle.Text = "SuperPlot "& a & "-"& b & "-"& m & "-"& n1 & "-"& n2 & "-" & n3 & "; "& nP
    .Axes(xlCategory, xlPrimary).HasTitle = True
    .Axes(xlCategory, xlPrimary).AxisTitle.Text = "X"
    .Axes(xlValue, xlPrimary).HasTitle = True
    .Axes(xlValue, xlPrimary).AxisTitle.Text = "Y"
End With
End Sub

29 July, 2023

Shapes Based On Equations: Cardioids

Cardioid curve is formed by tracing a point selected on the circumference of a circle, rolling onto another circle of the same radius. Here are two examples of cardioid graphics, one is just a single cardioid curve and the other is presentation of 4 cardioids positioned within the same coordinates.

These kind of graphics can be generated using the VBA macro listed below the two charts.

17 February, 2022

Picture in Picture in Excel Worksheet

What if you need to highlight/call attention to any fragment of your worksheet, be it a piece of data table or a picture/chart, for a presentation or just for printing a report?

You can do it quite easily in Excel. Let's consider a picture. You may need to overlay an enlarged small fragment of your picture onto the original whole picture. To do that you can use the Windows "Snip & Sketch" utility (the shortcut to invoke it, is: Windows Logo key + SHIFT + S). You can select either rectangular or free-form snip. After getting the snip, format/enlarge it as needed, in a way attracting attention to it, and move it to a desired position. This is an example of the 'picture in picture':

The same can be done also with any chart/graphics.

08 September, 2021

Goal Seek: Solving cubic equations

Let's say you you know the desired result of some formula, but you need to find possible input value(s) to achieve that result. You may even know the approximate values of those parameters. However, it's probably nothing more than guessing, and you need exact values.

In such cases it's better to use Excel's Goal Seek tool which helps to arrive at exact solutions very efficiently.

I'm providing here an example of using the Goal Seek. The example shows how to setup your worksheet for solving a cubic equation, such as Ac*x^3+Bc*x^2+Cc*x+Dc=0, where I renamed the coefficients a,b,c and d to Ac,Bc,Cc and Dc.

In this case we want to find the roots for this specific equation: