If graphs have multiple edges, then drawing them as straight lines does not show them when plotting the graphs; they will be on top of each other. One solution is to bend the edges, with diffenent curvature, so that all of them are visible.

## Arguments

- graph
The input graph.

- start
The curvature at the two extreme edges. All edges will have a curvature between

`-start`

and`start`

, spaced equally.

## Details

`curve_multiple()`

calculates the optimal `edge.curved`

vector for
plotting a graph with multiple edges, so that all edges are visible.

## See also

igraph.plotting for all plotting parameters,
`plot.igraph()`

, `tkplot()`

and `rglplot()`

for plotting functions.

## Author

Gabor Csardi csardi.gabor@gmail.com

## Examples

```
g <- make_graph(c(
0, 1, 1, 0, 1, 2, 1, 3, 1, 3, 1, 3,
2, 3, 2, 3, 2, 3, 2, 3, 0, 1
) + 1)
curve_multiple(g)
#> [1] -0.5000000 0.0000000 0.0000000 -0.5000000 0.0000000 0.5000000
#> [7] -0.5000000 -0.1666667 0.1666667 0.5000000 0.5000000
set.seed(42)
plot(g)
```