With this curve, the slope of the linear portion, which is the inverse of the compliance of the material, can be obtained. This is then used to derive f(c/a) as defined above in the equation. With the knowledge of all these variables, 
  
    
      
        
          
            K
          
          
            
              c
            
          
        
      
    
    {\textstyle \mathrm {K} _{\mathrm {c} }}
   can then be calculated. Ceramics and inorganic glasses
Ceramics and inorganic glasses have fracturing behavior that differ those of metallic materials. Ceramics have high strengths and perform well in high temperatures due to the material strength being independent of temperature.
This is done by taking the test piece with its fabricated notch of length 
  
    
      
        
          c
          ′
        
      
    
    {\textstyle \mathrm {c\prime } }
   and sharpening this notch to better emulate a crack tip found in real-world materials. Cyclical prestressing the sample can then induce a fatigue crack which extends the crack from the fabricated notch length of 
  
    
      
        
          c
          ′
        
      
    
    {\textstyle \mathrm {c\prime } }
    to 
  
    
      
        
          c
        
      
    
    {\textstyle \mathrm {c} }
  .