Sollya User's Manual

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taylor computes a Taylor expansion of a function in a point

taylor(function, degree, point) : (function, integer, constant) -> function

The command taylor returns an expression that is a Taylor expansion of function function in point point having the degree degree.

Let f be the function function, t be the point point and n be the degree degree. Then, taylor(function,degree,point) evaluates to an expression mathematically equal to f(t) + f'(t) * (x - t) + 1/2 * f''(t) * (x - t)^2 + ... + 1/(i!) * f[i](t) * (x - t)^i + ... + 1/(n!) * f[n](t) * (x - t)^n

Remark that taylor evaluates to 0 if the degree degree is negative.

> print(taylor(exp(x),5,0));
1 + x * (1 + x * (0.5 + x * (1 / 6 + x * (1 / 24 + x / 120))))

> print(taylor(asin(x),7,0));
x * (1 + x^2 * (1 / 6 + x^2 * (9 / 120 + x^2 * 225 / 5040)))

> print(taylor(erf(x),6,0));
x * (1 / sqrt((pi) / 4) + x^2 * ((sqrt((pi) / 4) * 4 / (pi) * (-2)) / 6 + x^2 * (sqrt((pi) / 4) * 4 / (pi) * 12) / 120))