Curve fitting equation & tracer software; pump curve and system curve plotting, intersection point of two curves, digitizing over existing graph image
Rethink, Reinvent . . . solve a task or two just-in-time
CurveFit Tracer - curve fitting software
> to obtain curve fitting equation from graph image/published graph
> to digitize graph
> to find complex intersection points of 2 curves
> to plot pump curves (1 or 2 identical pumps in parallel) and system curve with intersection point
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Curve Fit Tracer ... just point-and-click to get curve fitting equation
There are situations when you need to find a curve fit equation from the given graph image / published graph. Let's get stuff done in a simple yet effective way.
Trace Curve and Obtain Equation from given Graph Image
How do you find the equation of a curve from the graph?
For example, given the pump curves below, this app can trace the existing curve from the graph image/published graph, and obtain a curve fitting equation.
For linear-linear graph, curve fitting equations available are linear, parabolic and cubic to fifth order of polynomial equation.
Also available are power and exponential curve fitting.
For straight line on log-log graph plot, curve fitting equation is a power function.
You can copy & paste the equation for other purpose.
The program can be used as a simple graph digitizer too. Digitized X & Y data can be copied and pasted onto an Excel sheet for further processing.
For details, download these how-to documentations:
(1)Linear graph (2)Log-Log graph (3) Digitize log-log graph
Note: This app cannot do semi-log graph. For curve line on log-log graph, the program can digitize X & Y data for further processing.
Intersection Points
This app can find complex intersection points of 2 irregular lines as shown above.
You can key-in the points for the 2 lines, or generate points from equations.
The basic built-in equations to generate points are:
- linear line: y = c * x + k
- parabolic: y = b * x^2 + c * x + k
- cubic: y = a * x^3 + b * x^2 + c * x + k
- power: y = c * x^n
The comparison and validation results can be downloaded here.
Numerical Method: Line-Polynomial equation intersection points
see downloadable intersections example in applied pyschrometric
and Graphical Method
The following example shows the pump-system curves intersection point. The points are generated from the following equations:
Line 1 equation: Y = (12.1959750485299) X^0 + (-0.000313889819417844) X^1 + (-6.21374144873013E-08) X^2
Line 2 equation: Y = (0.0834768409254421) X^0 + (-0.000105670775146769) X^1 + (1.93568787397805E-07) X^2 + (-1.45541723653532E-12) X^3
1 or 2 Pump Curves and System Curve with intersect point
This app can plot pump curve for 1 or 2 identical pumps running in parallel, as well as a system curve with intersect point. See How-To example.
Final Thought: I wanted to obtain a curve fitting equation from an existing graph image, but I felt powerless to do so. So I created this application, and so on.
>> How To . . .
Related resources: see pump curve scaled plotting program: Pump Curve Scaled Plot
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CurveFit Tracer
Price: US $2.50
OS requirements: Windows Vista, 7, 8, 10
(Note: this software does not work on Windows XP).
