db2mag

Convert decibels (dB) to magnitude

Syntax

y = db2mag(ydb)

Description

y = db2mag(ydb) returns the magnitude measurements, y, that correspond to the decibel (dB) values specified in ydb. The relationship between magnitude and decibels is $$ydb=20\ast {\log }_{10}(y)$$

Examples

Magnitude of Elements in an Array

For this example, generate a 2-by-3-by-4 array of Gaussian random numbers. Assume the numbers are expressed in decibels and compute the corresponding magnitudes.

rng('default');
ydb = randn(2,3,4);
y = db2mag(ydb)

y = 
y(:,:,1) =

    1.0639    0.7710    1.0374
    1.2351    1.1044    0.8602


y(:,:,2) =

    0.9513    1.5098    0.8561
    1.0402    1.3755    1.4182


y(:,:,3) =

    1.0871    1.0858    0.9858
    0.9928    0.9767    1.1871


y(:,:,4) =

    1.1761    1.0804    1.0861
    1.1772    0.8702    1.2065

Use the definition to check the calculation.

chck = 10.^(ydb/20)

chck = 
chck(:,:,1) =

    1.0639    0.7710    1.0374
    1.2351    1.1044    0.8602


chck(:,:,2) =

    0.9513    1.5098    0.8561
    1.0402    1.3755    1.4182


chck(:,:,3) =

    1.0871    1.0858    0.9858
    0.9928    0.9767    1.1871


chck(:,:,4) =

    1.1761    1.0804    1.0861
    1.1772    0.8702    1.2065

Input Arguments

ydb — Input array in decibels

scalar | vector | matrix | array

Input array in decibels, specified as a scalar, vector, matrix, or an array. When ydb is nonscalar, db2mag is an element-wise operation.

Data Types: single | double

Output Arguments

y — Magnitude measurements

scalar | vector | matrix | array

Magnitude measurements, returned as a scalar, vector, matrix, or an array of the same size as ydb.

Version History

Introduced in R2008a