Truncate an infinite sum to its first 10 terms:

Truncate an infinite sum to a sum with a symbolic upper limit:

For unevaluated sums, TruncateSum directly evaluates the truncated sum:

Truncate a finite sum:

Truncate a sum with symbolic upper limit:

Truncate a sum with symmetric upper and lower limits:

Truncate an infinite sum:

Truncate a sum with doubly infinite limits:

Truncate a sum with –∞ as its lower limit:

Truncate a polynomial with infinite sum coefficients:

Truncate a doubly infinite sum:

Specify the maximum number of total terms for each sum:

Truncate only the first sum:

Truncate only the second sum:

Truncate a double sum:

Specify the maximum number of individual terms:

For inactive sums, TruncateSum tries to evaluate the truncated sum:

Use ActivateResultFalse to avoid activating the inactive sum:

Activate the result:

Truncate a double sum:

Truncate the sum using 20-digit precision arithmetic:

Solve the Dirichlet problem for the wave equation on a finite interval:

The solution is an infinite trigonometric series:

Extract the first three terms from the Inactive sum:

Solve the Dirichlet problem for the wave equation in a rectangle:

The solution is a doubly infinite trigonometric series:

Extract a few terms from the Inactive sums:

Solve the Dirichlet problem for the heat equation on a finite interval:

The solution is a Fourier sine series:

Truncate the Inactive sum:

Solve the initial value problem for a Schrödinger equation with Dirichlet boundary conditions:

Define a family of partial sums of the solution:

For each k, u_k satisfies the differential equation:

The boundary conditions are also satisfied:

The initial condition is only satisfied for u_∞, but there is rapid convergence at t==2:

Solve a difference equation:

Extract the solution for :

Compute the power series expansion of around 0:

Obtain the first seven nonzero terms in the series:

Compute the power series expansion of around 1:

Obtain the first five terms in the series:

Truncate the series for the Hypergeometric1F1 function:

Compare the results with the built-in Hypergeometric1F1 function:

Calculate the inverse Laplace transform of a function:

Truncate the sum and plot the result:

The inverse Laplace transform of this function is a piecewise function:

Truncate and plot the result: