# The Large Time-Frequency Analysis Toolbox

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# DEMO_ISGRAM - Contruction of a signal with a given spectrogram

## Description

This demo demonstrates iterative reconstruction of a spectrogram.

Original spectrogram

This figure shows the target spectrogram

Linear reconstruction

This figure shows a spectrogram of a linear reconstruction of the target spectrogram.

Iterative reconstruction using the Griffin-Lim method.

This figure shows a spectrogram of an iterative reconstruction of the target spectrogram using the Griffin-Lim projection method.

Iterative reconstruction using the BFGS method

This figure shows a spectrogram of an iterative reconstruction of the target spectrogram using the BFGS method.

This code produces the following output:

ISGRAMREAL: Iteration 10, residual = 0.571152.
ISGRAMREAL: Iteration 20, residual = 0.501330.
ISGRAMREAL: Iteration 30, residual = 0.469832.
ISGRAMREAL: Iteration 40, residual = 0.455037.
ISGRAMREAL: Iteration 50, residual = 0.448503.
ISGRAMREAL: Iteration 60, residual = 0.443755.
ISGRAMREAL: Iteration 70, residual = 0.438405.
ISGRAMREAL: Iteration 80, residual = 0.434859.
ISGRAMREAL: Iteration 90, residual = 0.432555.
ISGRAMREAL: Iteration 100, residual = 0.430852.