Numerical Integration

Hello,

I’m new on the forum, I’m student working on the field of chemistry, at the end of my Master theses. I use Igor for 3 years and I always found answer or first step for resolution on the forum but I’m actually lost for integral calculation.

I have to calculate the integral shows in the attached file were g(w) is an 1D function (phonon density of stats Vs w)

The only way I see is to program completely the integration with small rectangle, etc… Is there a tool with Igor to perform this sort of integral calculation?

Maybe someone can give me one of the these very useful “Display topics”.

Thanks in advance for your help,

 

Robert

 

 

phonon energy

Hello Robert,

Before you dive into executing Integrate1D please take a moment to evaluate a meaningful range of integration.  If you simply plug in values you will likely run into problems.  Consider, e.g., your lower integration limit: w=>0 =>exp()=>1 and ln(0) =>-inf.  In such situations you need to have g(w) provide bracketing so that the actual limits of integration are [a,b] with a>0 and b finite.

 

A.G.

 

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