TriangleWave
TriangleWave[x] gives a triangle wave that varies between -1 and +1 with unit period.
TriangleWave[{min, max}, x]gives a triangle wave that varies between min and max with unit period.
Examples
Plot[TriangleWave[x], {x, 0, 3}]Please visit the official Wolfram Language Reference for more details.