MATLAB: 1/X & X^-1 are they the same

reciprocals matlab

i'm about to write something that involves alot of reciprocals.
i want to know is 1/X the same as X^-1?
mathematically its the same, but which does matlab prefers? (that can make it simulate faster)
or are they really the same?

Best Answer

 clear all, clc
 ver
% ---------------------------------------------------------------------------

% MATLAB Version 7.13.0.564 (R2011b)
% OperatingSystem: MicrosoftWindows7 Version6.1 (Build7601: ServicePack1)
% Java VM Version: Java 1.6.0_17-b04 with Sun Microsystems Inc. 
% Java HotSpot(TM) Client VM mixed mode
% ---------------------------------------------------------------------------
 X = randn(100);
 for j = 1:5
    tic
    for i = 1:1e5
        invX1 = eye(100)/X;
    end
    time1(j) = toc              % 47.9   46.8   47.3   46.5   46.9
    tic
    for i = 1:1e5
        invX2 = X^(-1);
    end
    time2(j) = toc            %  62.6   62.8   62.6   61.9   62.3
    for i = 1:1e5
        invX3 = inv(X);
    end
    time3(j) = toc             %  98.7   96.3   96.5   97.8   97.2
 end
Hope this helps.
Greg
Related Question