Digital Library of Mathematical Functions
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6 Exponential, Logarithmic, Sine, and Cosine IntegralsProperties6.3 Graphics

Figure 6.3.3 (See in context.)

See accompanying text
Figure 6.3.3: |E1(x+y)|, -4x4, -4y4. Principal value. There is a cut along the negative real axis. Also, |E1(z)| logarithmically as z0.