Introduction to Numerical Sums, Products, and Integrals

NSum[f,{i,imin,Infinity}]numerical approximation to
NProduct[f,{i,imin,Infinity}]numerical approximation to
NIntegrate[f,{x,xmin,xmax}]numerical approximation to
NIntegrate[f,{x,xmin,xmax},{y,ymin,ymax}]
the multiple integral

Numerical sums, products, and integrals.

Here is a numerical approximation to :
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NIntegrate can handle singularities in the integration region:
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You can do numerical integrals over infinite regions:
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Here is a double integral over a triangular domain. Note the order in which the variables are given:
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Here is a double integral over a more complicated domain:
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