HeavisideLambda

HeavisideLambda[x] represents the triangle distribution Λ(x) which is nonzero for x<1.

HeavisideLambda[x1,x2,…] represents the multidimensional triangle distribution Λ(x1,x2,…) which is nonzero for xi<1.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.