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SUM function

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Adds the result of the argument to the previous result. This function is useful for evaluating Taylor series.

The SUM function differs from all other functions in 2 respects:

You are limited to 10 SUM functions in any equation (or pair of equations in the case of X=f(T),Y=g(T)).

The Prevent divide by zero errors feature of the Y=f(X) command and similar commands must be ignored when SUM is used in an equation. Division by 0 or other math error will result in an error message rather than incrementing X by a small value and re-evaluating.


A well-known (though very slow to converge) method for calculating π is:

which can be expressed in DPlot as:


The mathematician and astronomer Madhava of Sangamagrama found a series that converges much faster than the above:

which may be expressed in DPlot as


The first 20 terms of both series result in:

PI approximations, Taylor series


See also:



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