diff --git a/inversion.py b/inversion.py
new file mode 100644
index 0000000..73c2dd4
--- /dev/null
+++ b/inversion.py
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+import torch
+import torchvision
+import tqdm
+import torchvision.transforms as transforms
+from PIL import Image
+import warnings
+warnings.filterwarnings("ignore")
+
+
+
+### run inversion  (optimize PC coefficients) given single image
+def invert(network, unet, vae, text_encoder, tokenizer, prompt, noise_scheduler, epochs, image_path, mask_path, device, weight_decay = 1e-10, lr=1e-1):
+    ### load mask
+    if mask_path: 
+        mask = Image.open(mask_path)
+        mask = transforms.Resize((64,64), interpolation=transforms.InterpolationMode.BILINEAR)(mask)
+        mask = torchvision.transforms.functional.pil_to_tensor(mask).unsqueeze(0).to(device).bfloat16()
+    else: 
+        mask = torch.ones((1,1,64,64)).to(device).bfloat16()
+
+    ### single image dataset
+    image_transforms = transforms.Compose([transforms.Resize(512, interpolation=transforms.InterpolationMode.BILINEAR),
+                                                transforms.RandomCrop(512),
+                                                transforms.ToTensor(),
+                                                transforms.Normalize([0.5], [0.5])])
+
+
+    train_dataset = torchvision.datasets.ImageFolder(root=image_path, transform = image_transforms)
+    train_dataloader = torch.utils.data.DataLoader(train_dataset, batch_size=1, shuffle=True) 
+
+    ### optimizer 
+    optim = torch.optim.Adam(network.parameters(), lr=lr, weight_decay=weight_decay)    
+
+    ### training loop
+    unet.train()
+    for epoch in tqdm.tqdm(range(epochs)):
+        for batch,_ in train_dataloader:
+            ### prepare inputs
+            batch = batch.to(device).bfloat16()
+            latents = vae.encode(batch).latent_dist.sample()
+            latents = latents*0.18215
+            noise = torch.randn_like(latents)
+            bsz = latents.shape[0]
+         
+            timesteps = torch.randint(0, noise_scheduler.config.num_train_timesteps, (bsz,), device=latents.device)
+            timesteps = timesteps.long()
+            noisy_latents = noise_scheduler.add_noise(latents, noise, timesteps)
+            text_input = tokenizer(prompt, padding="max_length", max_length=tokenizer.model_max_length, truncation=True, return_tensors="pt")
+            text_embeddings = text_encoder(text_input.input_ids.to(device))[0]
+
+            ### loss + sgd step
+            with network:
+                model_pred = unet(noisy_latents, timesteps, text_embeddings).sample
+                loss = torch.nn.functional.mse_loss(mask*model_pred.float(), mask*noise.float(), reduction="mean")
+                optim.zero_grad()
+                loss.backward()
+                optim.step()
+
+    ### return optimized network
+    return network
+
+