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

.
| Out[1]= |  |
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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