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Cauchy Condensation Test

Compress slowly converging positive terms into dyadic blocks with honest bounds.

Free theory article

Compress slowly converging positive terms into dyadic blocks with honest bounds.

Concept & interpretation

The Cauchy Condensation Test is a standard convergence test in calculus, allowing us to determine the convergence of a series with positive, monotonically decreasing terms. The test compresses the sequence into "blocks" whose sizes are powers of 2. For a sequence an, it asserts that the sum of an converges if and only if the sum of 2ka2k converges.

Experiment

Open the Cauchy Condensation Test module.

  1. Set the Log exponent p control to 1.
  2. Set the Dyadic blocks control to 4.
  3. Observe that the Original partial sum is approximately 2.033.
  4. Notice the Infinite series result is Divergent, since p = 1.
  5. Change the Log exponent p to 2. The series now reports Convergent.
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