From 705f1a528b7ef299f7486181022600cfb641274f Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Mon, 11 Apr 2022 10:47:11 -0700
Subject: [PATCH] Separate functionality of ordinary linear interpolation from
 that using np.outer on arrays

---
 manimlib/utils/bezier.py | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/manimlib/utils/bezier.py b/manimlib/utils/bezier.py
index 16ec3e10..71d3d2b9 100644
--- a/manimlib/utils/bezier.py
+++ b/manimlib/utils/bezier.py
@@ -80,15 +80,10 @@ def partial_quadratic_bezier_points(
 
 # Linear interpolation variants
 
-def interpolate(start: T, end: T, alpha: float) -> T:
+
+def interpolate(start: T, end: T, alpha: np.ndarray | float) -> T:
     try:
-        if isinstance(alpha, float):
-            return (1 - alpha) * start + alpha * end
-        # Otherwise, assume alpha is a list or array, and return
-        # an appropriated shaped array of all corresponding
-        # interpolations
-        result = np.outer(1 - alpha, start) + np.outer(alpha, end)
-        return result.reshape((*np.shape(alpha), *np.shape(start)))
+        return (1 - alpha) * start + alpha * end
     except TypeError:
         log.debug(f"`start` parameter with type `{type(start)}` and dtype `{start.dtype}`")
         log.debug(f"`end` parameter with type `{type(end)}` and dtype `{end.dtype}`")
@@ -97,6 +92,15 @@ def interpolate(start: T, end: T, alpha: float) -> T:
         sys.exit(2)
 
 
+def outer_interpolate(
+    start: np.ndarray | float,
+    end: np.ndarray | float,
+    alpha: np.ndarray | float,
+) -> T:
+    result = np.outer(1 - alpha, start) + np.outer(alpha, end)
+    return result.reshape((*np.shape(alpha), *np.shape(start)))
+
+
 def set_array_by_interpolation(
     arr: np.ndarray,
     arr1: np.ndarray,