3D plots over the complex plane

Entering the complex plane

Upper picture: in the upper half of the near the real axis viewed from the lower half‐plane. Lower picture: in the lower half of the near the real axis viewed from the upper half‐plane. Here the complex variable is expressed as . The red surface is the real part of . The blue, semitransparent surface is the imaginary part of . The pink tube is the real part of the function along the real axis and the skyblue tube is the imaginary part of the function along the real axis. Along the real axis, inside the interval , the real part of is piecewise constant; going away from the real axis into the gives a function that approaches . Along the real axis, the imaginary part of vanishes identically outside the interval ; going away from the real axis into the is a function that approaches 0. The real part and the imaginary part are discontinuous along the branch cuts and . The real part and imaginary part have upper lip continuity in the right half‐plane and lower lip continuity in the left half‐plane. At , the function has a logarithmic singularity.

Branch cuts

The real part and the imaginary part of over the . The left graphic shows and the right graphic shows . Along the intervals , , the function has branch cuts. The imaginary part has discontinuities along the branch cuts. The branch points at are of square root type; the branch point at is af logarithmic branch point. The viewpoint is from the lower half‐plane.

The real part and the imaginary part of over the . The left graphic shows and the right graphic shows . is a regular point of . The viewpoint is from the upper half‐plane.

The branch cuts of the real part and the imaginary part of over the . The left graphic shows and the right graphic shows . The red and blue vertical surfaces connect points from the immediate lower and upper neighborhood of the branch cuts. The branch points at are of square root type; the branch point at is af logarithmic branch point. Only the imaginary part shows discontinuities due to the branch cuts. The viewpoint is from the lower half‐plane.

The branch cuts of the real part and the imaginary part of over the . The left graphic shows and the right graphic shows . The red and blue vertical surfaces connect points from the immediate lower and upper neighborhood of the branch cuts. is a regular point of . The viewpoint is from the upper half‐plane.

Real part over the complex plane

The real part of where . The surface is colored according to the imaginary part. The right graphic is a contour plot of the scaled real part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. Along the real axis the real part of approaches ; going away from the real axis into the upper half of the gives a function that also approaches with increasing imaginary part. The imaginary part is discontinuous along the branch cuts , .

The absolute value of the real part of where . The surface is colored according to the absolute value of the imaginary part. The right graphic is a contour plot of the scaled absolute value of the real part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. Along the real axis the real part of approaches ; going away from the real axis into the upper half of the gives a function that also approaches with increasing imaginary part. The real part is discontinuous along the branch cuts , .

Imaginary part over the complex plane

The imaginary part of where . The surface is colored according to the real part. The right graphic is a contour plot of the scaled imaginary part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. Along the real axis, the imaginary part of vanishes identically outside the branch cut intervals , ; going away from the real axis into the gives a function that approaches as . is a discontinuous function over the . The branch points at are of square root type; the branch point at is a logarithmic branch point.

The absolute value of the imaginary part of where . The surface is colored according to the absolute value of the real part. The right graphic is a contour plot of the scaled absolute value of the imaginary part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. Along the real axis, the imaginary part of vanishes identically outside the branch cut intervals , ; going away from the real axis into the gives a function that approaches as . The branch points at are of square root type; the branch point at is af logarithmic branch point.

Absolute value part over the complex plane

The absolute value of where . The surface is colored according to the argument. The right graphic is a contour plot of the scaled absolute value, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. The logarithmic singularity at is visible.

Argument over the complex plane

The argument of where . The surface is colored according to the absolute value. The right graphic is a contour plot of the scaled argument, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. has lines of discontinuities over the .

The square of the sine of the argument of where . For dominantly real values, the function value are near 0, and for dominantly imaginary values, the function values are near 1. The surface is colored according to the absolute value. The right graphic is a cyclically colored contour plot of the argument. Red represents arguments near and light‐blue represents arguments near 0.

Zero-pole plot

The logarithm of the absolute value of where in the upper half‐plane. The surface is colored according to the square of the argument. In this plot zeros are easily visible as spikes extending downwards and poles and logarithmic singularities as spikes extending upwards. The logarithmic singularity at is visible.

Real part over the complex plane near infinity

The real part of where . The surface is colored according to the imaginary part.The right graphic is a contour plot of the scaled real part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. At the function has no singularity.

The absolute value of the real part of where . The surface is colored according to the absolute value of the imaginary part. The right graphic is a contour plot of the scaled absolute value of the real part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest.

Imaginary part over the complex plane near infinity

The imaginary part of where . The surface is colored according to the real part. The right graphic is a contour plot of the scaled imaginary part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. At the function has no singularity.

The absolute value of the imaginary part of where . The surface is colored according to the absolute value of the real part. The right graphic is a contour plot of the scaled absolute value of the imaginary part, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. At the function has no singularity.

Absolute value part over the complex plane near infinity

The absolute value of where . The surface is colored according to the argument. The right graphic is a contour plot of the scaled absolute value, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. At the function has no singularity.

Argument over the complex plane near infinity

The argument of where . The surface is colored according to the absolute value. The right graphic is a contour plot of the scaled argument, meaning the height values of the left graphic translate into color values in the right graphic. Red is smallest and violet is largest. At the function has no singularity.

The square of the sine of the argument of where . For dominantly real values, the function values are near 0, and for dominantly imaginary values, the function values are near 1. The surface is colored according to the absolute value. The right graphic is a cyclically colored contour plot of the argument. Red represents arguments near and light‐blue represents arguments near 0.

Zero-pole plot near infinity

The logarithm of the absolute value of where in the upper half‐plane. The surface is colored according to the square of the argument. In this plot zeros are easily visible as spikes extending downwards and poles and logarithmic singularities as spikes extending upwards. At the function has no singularity.