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Date: Sun, 9 May 2010 03:08:06 +0000 (UTC)
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"Romiza " <rrm_romi@hotmail.com> wrote in message <hs51m5$aqt$1@fred.mathworks.com>...
> Hi,
> 
> I am seeking some help, I have developed he follwing file to obtain some graphs, however now i need to get the gradient of it and have no idea how to go about it. Could someone please help me:
> 
> My file is below:
> x = linspace 0; 180; 10;
> y = 7.657*log(x)+28.206;
> plot (x, y, '--');
> xlabel('Time (minutes)')
> ylabel ('Concentration (g/L)')
> hold on
> y = 7.0516*log(x)+21.051;
> plot (x, y, 'o');
> y = 5.948*log(x)+17.64;
> plot (x, y, 's');
> y = 9.6964*log(x)+25.292;
> plot (x, y, '-');
> hold off
> 
> 
> Thank you

  What's wrong with using your knowledge of calculus to evaluate the derivative of log(x) directly?  That's what the gradient is along these one-dimensional curves.

Roger Staffod