The function subtract(a, b) returns the formal power series in which each coefficient is the corresponding coefficient of a minus the corresponding coefficient of b.

This function yields the same result as powadd(a, negative(b)), but is faster.

The command with(powseries,subtract) allows the use of the abbreviated form of this command.

$\mathrm{with}\left(\mathrm{powseries}\right)\:$

$\mathrm{powcreate}\left(t\left(n\right)=\frac{t\left(n-1\right)}{n}\,t\left(0\right)=1\right)\:$

$\mathrm{powcreate}\left(v\left(n\right)=\frac{v\left(n-1\right)}{2}\,v\left(0\right)=1\right)\:$

$s≔\mathrm{subtract}\left(v\,t\right)\:$

$\mathrm{tpsform}\left(s\,x\,6\right)$

$-\frac{1}{2}x-\frac{1}{4}{x}^2-\frac{1}{24}{x}^3+\frac{1}{48}{x}^4+\frac{11}{480}{x}^5+O\left(x^6\right)$