Post Closed as "off topic" by Douglas Zare, Willie Wong, Pietro Majer, Michael Renardy, George Lowther

show/hide this revision's text 2 edited body

Let $g$ be Riemann integrable on $[a,b]$, $f(x)=\int_a^xg(t)dt$ for $x∈[a,b]$.

How to show that the total variation of $f$ is equal to $∫_b^a|g(x)|dx$?∫_a^b|g(x)|dx$?

show/hide this revision's text 1

Question about Riemann integral and total variation

Let $g$ be Riemann integrable on $[a,b]$, $f(x)=\int_a^xg(t)dt$ for $x∈[a,b]$.

How to show that the total variation of $f$ is equal to $∫_b^a|g(x)|dx$?